This paper proposes a best node and random jammer (bN-rJ) scheme for multi-hop Internet-of-Things (IoT) networks under imperfect channel state information (CSI) and non-colluding eavesdroppers. Approximate and asymptotic closed-form expressions for the secrecy block-error rate (SBLER) and secrecy throughput (STP) of the bN-rJ scheme are derived, thereby guiding useful insights into system designs. Numerical results reveal that: 1) For perfect CSI cases, the bN-rJ scheme offers better secrecy improvement than the benchmark ones, especially saving over 10 dB power for SBLER transmission and increasing at least 0.5 bit per channel use in STP performance; 2) For imperfect CSI (iCSI), SBLER can be reduced significantly when using node selection strategy, for example, on average reduction of 2×10-1 with 10 nodes at an iCSI level of 0.6; 3) The optimal transmission hop of the bN-rJ scheme under perfect CSI is always larger than its counterpart under iCSI at least 1 hop in STP evaluation.
This paper proposes a best node and random jammer (bN-rJ) scheme for multi-hop Internet-of-Things (IoT) networks under imperfect channel state information (CSI) and non-colluding eavesdroppers. Approximate and asymptotic closed-form expressions for the secrecy block-error rate (SBLER) and secrecy throughput (STP) of the bN-rJ scheme are derived, thereby guiding useful insights into system designs. Numerical results reveal that: 1) For perfect CSI cases, the bN-rJ scheme offers better secrecy improvement than the benchmark ones, especially saving over 10 dB power for SBLER transmission and increasing at least 0.5 bit per channel use in STP performance; 2) For imperfect CSI (iCSI), SBLER can be reduced significantly when using node selection strategy, for example, on average reduction of 2×10-1 with 10 nodes at an iCSI level of 0.6; 3) The optimal transmission hop of the bN-rJ scheme under perfect CSI is always larger than its counterpart under iCSI at least 1 hop in STP evaluation.
In this paper, we propose a best node and friendly jammer (bN-fJ) scheme for secure short-packet multi-hop communications in Internet-of-Things (IoT) networks. Under imperfect channel state information (CSI) conditions, the best IoT node is chosen for data transmission and a friendly jammer is chosen later to confuse the received signals at a multi-antenna eavesdropper. Approximate and asymptotic closed-form expressions for the secrecy throughput of the bN-fJ scheme are obtained, offering valuable insights into the system designs. Numerical results show that the proposed bN-fJ scheme achieves much better performance than benchmarking schemes, especially with 1 more bit/channel use and 9.4 dB enhancement in communication reliability measure. Moreover, under imperfect CSI and large antennas at the eavesdropper, the secrecy throughput and communication reliability of the system can be improved by employing the proposed node selection, e.g., a 12.5 dB improvement at 10 antennas at Eve and the imperfect CSI of 0.8. Finally, the secrecy throughput is presented as a concave curve for the number of hops and blocklengths, which enables us to identify the optimal hops and blocklength for secure multi-hop short-packet transmissions.
This paper studies the secrecy performance of short-packet communications in dual-hop cooperative Internet-of-Things (IoT) networks in the presence of multiple eavesdroppers. The best node selection (BNS) scheme is proposed to select the best IoT node for improving secure packet transmissions from a source to a robot destination under two intercepting scenarios at eavesdroppers such as non-colluding and colluding. Closed-form expressions for the average secrecy block error rate (SBLER) and secrecy throughput (STP) of the BNS scheme are derived, based on which the asymptotic analysis at high signal-to-noise ratio (SNR) regimes is also carried out. Simulation results show that the proposed BNS scheme outperforms the random selection one in terms of SBLER and STP. Moreover, the impacts of average SNR and the number of blocklengths on the system STP are also evaluated.
As the number of connected devices is exponentially increasing, security in Internet of Things (IoT) networks presents a major challenge. Accordingly, in this work we investigate the secrecy performance of multihop IoT networks assuming that each node is equipped with only two antennas, and can operate in both Half-Duplex (HD) and Full-Duplex (FD) modes. Moreover, we propose an FD Cooperative Jamming (CJ) scheme to provide higher security against randomly located eavesdroppers, where each information symbol is protected with two jamming signals by its two neighbouring nodes, one of which is the FD receiver. We demonstrate that under a total power constraint, the proposed FD-CJ scheme significantly outperforms the conventional FD Single Jamming (FD-SJ) approach, where only the receiving node acts as a jammer, especially when the number of hops is larger than two. Moreover, when the Channel State Information (CSI) is available at the transmitter, and transmit beamforming is applied, our results demonstrate that at low Signal-to-Noise Ratio (SNR), higher secrecy performance is obtained if the receiving node operates in HD and allocates both antennas for data reception, leaving only a single jammer active; while at high SNR, a significant secrecy enhancement can be achieved with FD jamming. Our proposed FD-CJ scheme is found to demonstrate a great resilience over multihop networks, as only a marginal performance loss is experienced as the number of hops increases. For each case, an integral closed-form expression is derived for the secrecy outage probability, and verified by Monte Carlo simulations.
In this work, we exploit a multi-antenna cooperative jammer to enable secure short packet communications in Internet of Things (IoT) networks. Specifically, we propose three jamming schemes to combat eavesdropping, i.e., the zero forcing beamforming (ZFB) scheme, null-space artificial noise (NAN) scheme, and transmit antenna selection (TAS) scheme. Assuming Rayleigh fading, we derive new closed-form approximations for the secrecy throughput with finite blocklength coding. To gain further insights, we also analyze the asymptotic performance of the secrecy throughput in the case of infinite blocklength. Furthermore, we investigate the optimization problem in terms of maximizing the secrecy throughput with the latency and reliability constraints to determine the optimal blocklength. Simulation results validate the accuracy of the approximations and evaluate the impact of key parameters such as the jamming power and the number of antennas at the jammer on the secrecy throughput.
This paper investigates the secrecy performance of a hardware-impaired secure rate-splitting multiple access (HIS-RSMA) network in multi-user multiple-input single-output (MISO) Internet of Things (IoT) scenarios over Nakagami-mfading channels. Closed-form expressions for the secrecy capacity (SC) and secrecy outage probability (SOP) are derived and validated through Monte-Carlo simulations. The proposed analytical framework explicitly accounts for the joint effects of non-ideal hardware (NIH), imperfect successive interference cancellation (SIC), and imperfect channel state information (CSI), thereby providing a realistic evaluation of secrecy in IoT networks. Numerical results reveal that NIH has a negligible impact on the secrecy of the common message but significantly degrades the secrecy of private messages at high transmit powers. Moreover, both NIH and imperfect SIC introduce non-vanishing SOP error floors, while imperfect CSI at the eavesdropper can substantially enhance secrecy. The number of transmit antennas and the operating frequency are also shown to critically influence secrecy performance. Overall, the findings highlight that HIS-RSMA is a promising solution for secure and efficient transmission in IoT networks, underscoring the need for joint optimization of transceiver design, antenna configuration, and physical-layer security strategies in beyond fifth-generation (B5G) wireless systems.
In this article, we consider physical-layer security (PLS) of the Internet-of-Things (IoT) communications based on hybrid automatic repeat request (HARQ) protocols in multiple-input single-output single-eavesdropper (MISOSE) channels. Owing to the reciprocity of wireless channels, a negative acknowledge frame can be used to obtain the channel state information (CSI) from a source with multiple antennas to an IoT destination device, and this CSI of a legitimate link is used for beamforming for the next transmission round (TR). Therefore, a higher secrecy rate can be expected from retransmissions with beamforming based on the CSI as compared to the first TR without CSI. To evaluate the secrecy throughput under time-invariant and time-varying channels, connection and secrecy outage probabilities (OPs) are derived. By exploiting the characteristics of the OPs, we suggest an approximated secrecy throughput. We then consider the optimization of the approximated secrecy throughput considering the rate parameters for legitimate and eavesdropping links. With an alternating optimization approach, an algorithm to find convergent system parameters, i.e., the rates for legitimate and eavesdropping links, is proposed. Moreover, an asymptotic analysis with the large number of transmit antennas indicates an interesting behavior of the secrecy rate with regard to the number of TRs. The analytical results are verified by rigorous numerical simulations and they can serve as a useful guideline to those involved in the design of secure IoT communication systems with HARQ in MISOSE channels.