Exploiting Full-Duplex Receivers for Achieving Secret Communications in Multiuser MISO Networks

Abstract

We consider a broadcast channel, in which a multi-antenna transmitter (Alice) sends K confidential information signals to K legitimate users (Bobs) in the presence of L eavesdroppers (Eves). Alice uses MIMO precoding to generate the information signals along with her own (Tx-based) friendly jamming. Interference at each Bob is removed by MIMO zero-forcing. This, however, leaves a "vulnerability region" around each Bob, which can be exploited by a nearby Eve. We address this problem by augmenting Tx-based friendly jamming (TxFJ) with Rxbased friendly jamming (RxFJ), generated by each Bob. Specifically, each Bob uses self-interference suppression (SIS) to transmit a friendly jamming signal while simultaneously receiving an information signal over the same channel. We minimize the powers allocated to the information, TxFJ, and RxFJ signals under given guarantees on the individual secrecy rate for each Bob. The problem is solved for the cases when the eavesdropper's channel state information is known/unknown. Simulations show the effectiveness of the proposed solution. Furthermore, we discuss how to schedule transmissions when the rate requirements need to be satisfied on average rather than instantaneously.Under special cases, a scheduling algorithm that serves only the strongest receivers is shown to outperform the one that schedules all receivers. Index termsBroadcast channel, channel correlation, friendly jamming, full-duplex, physical layer security I. INTRODUCTIONAs wireless systems continue to proliferate, confidentiality of their communications becomes one of the main concerns due to the broadcast nature of the wireless medium. Cryptographic techniques can be utilized to address these concerns, but such techniques often assume adversaries with limited computational capabilities. Physical (PHY) layer security, on the other hand, can be implemented regardless of the adversary's computational power. It also takes advantage of the characteristics of the wireless medium.The authors are with the The origins of PHY-layer security dates back to the pioneering work of Wyner [1] that studied the concept of secrecy capacity for the degraded wiretap channel. The authors in [2] extended Wyner's work to non-degraded discrete memoryless broadcast channels. Later on, the secrecy capacity of MIMO (multiple-input multiple-output) wiretap channel was obtained in [3]. The secrecy region of the Gaussian MIMO broadcast channel was studied in [4], [5], and [6]. The authors in [7] and [8] studied the problem of secure communications over broadcast channels under individual secrecy constraint, which guarantees that the information leakage to eavesdroppers from each information message vanishes. Even though the joint secrecy constraint, which ensures that the information leakage to eavesdroppers from all information messages vanishes, is stronger than the individual one, it is not always possible to satisfy. Moreover, the individual secrecy constraint still offers an acceptable secrecy level, while increasing transmission rates [7]. T...

A Survey of Optimization Approaches for Wireless Physical Layer Security

“…Multiuser MISO networks with jamming [192] The total power for secrecy information and jamming signals Perfect CSI of all channels Target secrecy rate Numerical analyses based on a line search method A non-orthogonal multiple access system with multiple users [193] Decoding order, transmission rates, and power Instantaneous channel gains of all users and the average channel gain of the eavesdropper Target secrecy rate and secrecy outage probability A closed-form solution by problem simplification Traffic offloading via dual-connectivity in cellular networks [194] Data rate and transmission power Perfect CSI of legitimate channel and statistics CSI of eavesdropper Traffic demand and secrecy outage requirement Performing a series of equivalent transformations and proposing an efficient algorithm to compute the optimal offloading solution jointly optimized to minimize the outage probability for delaylimited secrecy information transmission based on the approaches of dual decomposition and alternating optimization. In [189], the minimum secrecy outage probability is achieved by optimizing the optimal placement of energy harvesting node with physical layer security considerations.…”

“…In a MISO system in [86], the optimal power allocation between transmitted information and AN is developed for minimizing the transmission power while ensuring a given probability of secrecy. In [192] where a multiuser MISO network with friendly jamming is considered, the power allocation strategy is optimized to minimize the total power allocated to the information signals and jamming signals while maintaining secure QoS requirements. A non-orthogonal multiple access system is considered in [193] where a closed-form solution is derived to minimize the transmission power.…”

A New Design Paradigm for Secure Full-Duplex Multiuser Systems

“…The work in [20] considered a MIMO Gaussian wiretap channel with an FD jamming receiver to secure the DoF. The authors in [21] extended the prior work to a multiuser scenario, where the transmitter is equipped with multiple antennas to guarantee the individual SR for multiple users. However, these approaches require high hardware complexity of the receivers, which may be difficult to achieve in practice because the end devices should be of very low complexity.…”

“…As a result, the CSI of Eves may change, and thus, FD-BS and UL users can only estimate Eves' channel statistics based on their last known CSI. In this section, we consider the case in which the FD-BS and UL users have perfect CSI of all legitimate users as explained in Section III, but only the statistics of CSI for Eves (i.e., the first-order and second-order statistics) [16], [21] as follows:H…”

Asymptotic Bound of Secrecy Capacity for MIMOME‐Based Transceivers: A Suboptimally Tractable Solution for Imperfect CSI

“…The MIMO channels between the legitimate transmitter and the legitimate user as well as Eave are principally denoted by H and G (please note that our scheme undoubtedly satisfies H and G of sizes × and ̸ = ; however, we considered them as × (square) for more convenience), in a Down-link paradigm. For G, we experience imperfect knowledge (which degrades QoS): that is, G ≜ G 1 ± Γ (our scheme is not applicable for some other frameworks [25,26] in which, for example, the channel matrix is an arbitrary known matrix physically multiplied by a clear matrix [27, p. 4]). Now, regarding the threshold , for G we merely define the ellipsoidal uncertainty set Γ ≜ {Γ ∈ C × : ‖Γ‖ 2 ⩽ }.…”