Secure Directional Modulation With Few-Bit Phase Shifters: Optimal and Iterative-Closed-Form Designs

Abstract

In this paper, directional modulation (DM) is investigated to enhance physical layer security. Practical transmitter designs are exploited under imperfect channel state information (CSI) and hardware constraints, such as finite-resolution phase shifters (PSs) and per-antenna power budget. Tailored for the practical issues in realizing DM, a series of practical scenarios are investigated. Starting from the scenario where eavesdroppers (Eve)s' information is completely unknown, corresponding designs are proposed to optimize legitimate users (LU)s' receiving performance while randomizing the Eves' received signal. When the Eves' CSI is imperfectly known, in the second scenario, the Eves' receiving performance is further deteriorated by imposing destructive interference to the Eves. For each scenario, three algorithms are proposed under hardware constraints and imperfect CSI, i.e. one direct-mapping algorithm suitable for high/moderate number of bits in PSs, one heuristic algorithm with improved receiving performance at the cost of complexity, and one iterativeclosed-form algorithm with enhanced practicality of symbol-level based DM. Simulation demonstrates that the algorithms achieve lower symbol error rate (SER) at the LUs while significantly deteriorating the Eves' SER, leading to an improved secrecy throughput over the benchmarks.

Compressive Sensing-Based Secure Uplink Grant-Free Systems

“…Since the existing channel estimation techniques rely on the specific pilot matrix in grant-free communications, the constant pilot matrix may introduce serious security problems when an eavesdropper has the knowledge of the pilot information. In this context, the physical layer security draws lot of attention Wei et al (2022) Wei et al (2021b). Rachlin and Baron (2008) showed that the CS-based encryption does not achieve Shannon's definition of perfect secrecy, but a computationally unbounded adversary can easily infer that the correct sparse signal has been recovered.…”

Interference Utilization Precoding in Multi-Cluster IoT Networks

“…In this case, there is scope to jointly exploit the correlation among the channels and transmitted data, so that the multi-user interference is possible to make constructive at each receiver, termed as interference utilization (IE) precoding (Masouros and Alsusa, 2007). The concept of constructive interference (CI) has been applied for anonymous communications (Wei et al, 2021a), cognitive radio (Law and Masouros, 2018), large-scale MIMO Masouros, 2016, 2017b), constant envelope (Amadori and Masouros, 2017a;Liu et al, 2017), hybrid beamforming (Hegde et al, 2019), multicell coordination (Wei et al, 2020b), rate-splitting (Salem et al, 2019), physical layer security (Khandaker et al, 2019;Wei et al, 2020a;Wei and Masouros, 2020), directional modulation (Wei et al, 2021b), and integrated sensing and communication systems (Liu et al, 2018). In the following section, we briefly discuss the IE-based precoder design.…”

Constructive Interference based Joint Combiner and Precoder Design in Multiuser MIMO Systems

“…Then a rotated ZF-based scheme was proposed in [11] to partially utilize interference, and [12] further proposed that all the interference can be constructive by precoder design operating at symbol level. Recently, CI was applied into generic multiple-input and singleoutput (MISO) systems [13] [14] [15], large-scale MIMO [16], hybrid beamforming [17], multi-cell coordination [18], and physical layer security [19].…”