Exploiting Direct Links for Physical Layer Security in Multiuser Multirelay Networks

Abstract

Abstract-We present two physical layer secure transmission schemes for multi-user multi-relay networks, where the communication from M users to the base station is assisted by direct links and by N decode-and-forward relays. In this network, we consider that a passive eavesdropper exists to overhear the transmitted information, which entails exploiting the advantages of both direct and relay links for physical layer security enhancement. To fulfill this requirement, we investigate two criteria for user and relay selection and examine the achievable secrecy performance. Criterion I performs a joint user and relay selection, while Criterion II performs separate user and relay selections, with a lower implementation complexity. We derive a tight lower bound on the secrecy outage probability for Criterion I and an accurate analytical expression for the secrecy outage probability for Criterion II. We further derive the asymptotic secrecy outage probabilities at high transmit signal-to-noise ratios and high main-to-eavesdropper ratios for both criteria. We demonstrate that the secrecy diversity order is min (M N, M + N ) for Criterion I, and N for Criterion II. Finally, we present numerical and simulation results to validate the proposed analysis, and show the occurrence condition of the secrecy outage probability floor.Index Terms-Physical layer security, multi-user multi-relay networks, direct links, secrecy outage probability, secrecy diversity order.

Performance Analysis of Physical Layer Security of Opportunistic Scheduling in Multiuser Multirelay Cooperative Networks

“…Herein, we set $ϵ=4$ (for an urban environment). The main-to-eavesdropper ratio (MER) can be defined as the ratio of the average main channel gain over the average eavesdropper channel gain in one hop [16,25], i.e., ${\mathrm{MER}}_1=\frac{{\lambda }_{\mathrm{SR}}}{{\lambda }_{\mathrm{SE}}}$ and ${\mathrm{MER}}_2=\frac{{\lambda }_{\mathrm{RD}}}{{\lambda }_{\mathrm{RE}}}$. Without loss of generality, in our simulation, we set ${\mathrm{MER}}_1={\mathrm{MER}}_2=\mathrm{MER}$.…”

“…fading, for the sake of notational convenience, let ${\lambda }_{{\mathrm{S}}_m{\mathrm{R}}_n}={\lambda }_{\mathrm{SR}}$, ${\lambda }_{{\mathrm{S}}_m\mathrm{normalE}}={\lambda }_{\mathrm{SE}}$, ${\lambda }_{{\mathrm{R}}_n\mathrm{normalD}}={\lambda }_{\mathrm{RD}}$ and ${\lambda }_{{\mathrm{R}}_n\mathrm{normalE}}={\lambda }_{\mathrm{RE}}$. In addition, we assume that the source and the relay use the same transmit power, i.e., $P_{{\mathrm{normalS}}_m}=P_{{\mathrm{normalR}}_n}=P$, and all nodes have the same noise variance, i.e., ${\sigma }_{{\mathrm{R}}_n}^2={\sigma }_{\mathrm{normalD}}^2={\sigma }_{\mathrm{normalE}}^2={\sigma }^2$, as in [16,17,25]. It is noteworthy that the assumptions of using the same transmit powers and identical noise variances do not lose the generality of the developed analysis.…”

Performance evaluation of amplify‐and‐forward relaying cooperative vehicular networks under physical layer security

“…which can be evaluated by substituting the CDF F Ψ 1 (x) from (11) along with the PDF of SD into (13) and simplifying the required integral as…”

“…To do so, we first need to derive the asymptotic expression of the CDF of Λ D . Therefore, under Scenario I, by applying the approximation e −x ≈ x→0 1 − x into (B2) and invoking the result along with the PDF of SD into (13), and…”

“…8 PHY-security can be implemented without consuming the additional communication resources or infrastructures, and it can guarantee information confidentiality with the aid of appropriate coding and signal processing techniques. Recently, PHY-security in cooperative relaying networks has been widely studied in the literature (see other works [9][10][11][12][13][14][15][16][17][18][19] and the references therein). Specifically, Zou et al, 9 Yang et al, 10 and Nguyen and Kim 11 have investigated the secrecy performance of cooperative multirelay networks with optimal relay selection scheme.…”