Achieving negative security gaps with transmit antenna selection and frame scrambling in quasi‐static fading channels

Abstract

The security gap of a wireless network composed of two legitimate nodes and one eavesdropper, all provided with multiple antennas, is evaluated. The use of transmit antenna selection combined with frame scrambling may lead to gaps <0 dB, under feasible scrambling depths and a practical number of transmit antennas is shown.

On the Security Gap of Convolutional-Coded Transmit Antenna Selection Systems

“…As n A increases, less link quality is needed to achieve the same performance, making the approximation to be less accurate. That means that the actual results (in terms of required security gap) can be even smaller than those found in [15].…”

“…The upper bound FER is calculated by simulating the effect of (6) (referred to as "semi-analytical" approach). From the Security gap calculated by theoretical equation using outage probability, approximation from [15], semi-analytical approach using FER of Standard NASA convolutional code with rate 1/2 (constraint length 7 and generator polynomial in octal [133,171]) and N = 256 bits, and the simulation of this same code. Considering n A ∈ [2,4,10].…”

“…However, this is not true when we consider n A = 10. This behavior can be explained analyzing the approximate equation which is only valid toγ 1 [15]. As n A increases, less link quality is needed to achieve the same performance, making the approximation to be less accurate.…”

“…Some preliminary results on the outage probability-based security gap in a MIMO scenario, where Alice adopts the transmit antenna selection (TAS) scheme [13], [14] while both Bob and Eve operate under the maximum ratio combining (MRC) scheme [13], are presented in [15] showing the benefits of employing TAS along with scrambling towards reducing the security gap. One important feature of TAS is that it requires a minimal amount of feedback (just the index of the best antenna).…”

“…In this work, under the same framework as [15], we resort to the inverse gamma function to obtain an exact expression to the outage probability-based security gap, in order to validate the accuracy of the approximation introduced in [15]. Moreover, we also evaluate the performance of the proposed scheme by adopting a more realistic FER-based security gap formulation, which is calculated supposing the use of convolutional codes.…”