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

Abstract

In this work we evaluate the security gap of a network composed of two legitimate nodes and one passive eavesdropper, all of them provided with multiple antennas. We consider that transmit antenna selection (TAS) along with frame scrambling is adopted at the transmitter node, while both legitimate and malicious receivers operate under the maximum ratio combining (MRC) protocol. By considering a quasi-static fading scenario, we evaluate (analytically and through numerical results) the security gap in terms of both outage probability and frame error rate (when using convolutional codes), showing that in both situations it is possible to achieve negative security gaps using a feasible number of antennas.

Security Gap of Coded Transmit Antenna Selection Systems with Frame Scrambling

“…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. The results in [1] confirm that, either considering outage probability or FER as the reliability metric, it is possible to achieve a security gap lower than 0 dB under feasible scrambling depths and using practical number of antennas, which means that secure communication is feasible even if the channel between Alice and Eve is in better conditions, in average, than the channel between Alice and Bob.…”

“…A preliminary version of this paper was presented in XXXIII Simpósio Brasileiro de Telecomunicações (SBrT'15), Juiz de Fora, MG, Brazil, September 1-4, 2015 [1].…”

“…Some preliminary results on the outage probability-based security gap in a MIMO scenario, where Alice adopts the transmit antenna selection (TAS) scheme [15], [16] while both Bob and Eve operate under the maximum ratio combining (MRC) scheme [15], are presented in [1], [17] 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 [1], under the same framework as [17], 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 [17]. 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.…”

“…This work aims at presenting an extension of [17] and [1], including further analysis and discussions about both the perfect and more practical scrambling-based scenarios, as well as a more detailed mathematical analysis regarding the convolutional codes. Our results show that the perfect scrambling-based security gap presents a very similar result to the practical case, while being much easier to be calculated.…”