On Security and Throughput for Energy Harvesting Untrusted Relays in IoT Systems Using NOMA

Abstract

In this paper, we analyze the secrecy and throughput of multiple-input single-output (MISO) energy harvesting (EH) Internet of Things (IoT) systems, in which a multi-antenna base station (BS) transmits signals to IoT devices (IoTDs) with the help of relays. Specifically, the communication process is separated into two phases. In the first phase, the BS applies transmit antenna selection (TAS) to broadcast the signal to the relays and IoTDs by using non-orthogonal multiple access (NOMA). Here, the relays use power-splitting-based relaying (PSR) for EH and information processing. In the second phase, the selected relay employs the amplify-and-forward (AF) technique to forward the received signal to the IoTDs using NOMA. The information transmitted from the BS to the IoTD risks leakage by the relay, which is able to act as an eavesdropper (EAV) (i.e., an untrusted relay). To analyze the secrecy performance, we investigate three schemes: random-BS-best-relay (RBBR), best-BS-random-relay (BBRR), and best-BS-best-relay (BBBR). The physical layer secrecy (PLS) performance is characterized by deriving closed-form expressions of secrecy outage probability (SOP) for the IoTDs. A BS transmit power optimization algorithm is also proposed to achieve the best secrecy performance. Based on this, we then evaluate the system performance of the considered system, i.e., the outage probability and throughput. In addition, the impacts of the EH time, the power-splitting ratio, the numbers of BS antennas, and the numbers of untrusted relays on the SOP and throughput are investigated. The Monte Carlo approach is applied to verify our analytical results. Finally, the numerical examples indicate that the system performance of BBBR is greater than that of RBBR and BBRR.INDEX TERMS Energy harvesting, Internet of Things, physical layer secrecy, throughput, NOMA, MISO, untrusted relay.

HARQ Assisted Short-Packet Communications for Cooperative Networks Over Nakagami-m Fading Channels

“…where Φ l S denotes the event that the user correctly decodes its intended message in the lth transmission. (12) shows the sum of average transmission rate in a successful transmission process multiplying its corresponding probability.…”

“…Zhang et al [11] aimed to many-to-many-to-one Internet of things (IoT) networks and designed a joint thing and relay selection criteria for balancing the performance and fairness. Consid-ering the limited power in IoT, an energy harvesting IoT system was proposed in [12], where relays are utilized to help the base station transmits signals to IoT devices. Besides, Shabbir et al [13] considered a full-duplex relay with energy harvesting capability and proposed amplifying and forward (AF), and decode and forward (DF) relaying protocols for IoT networks.…”

Secure Communication in Cooperative SWIPT NOMA Systems with Non-Linear Energy Harvesting and Friendly Jamming

“…The LEH model assumes a linear relationship P EH = ηP Rx at the harvester where η is energy conversion efficiency. However, measurements in [25,26] show the non-linear relationship between P Rx and P EH which is well modeled using a logistic function as [18]…”

“…Proof. (18) and (19) are obtained via solving F Z (z) = Pr g RE < g JE P J P R,n z and f Z (z) = ∂ ∂z F Z (z), respectively.…”

“…To guarantee security in multi-user networks, the studies on secure communication of SWIPT-based NOMA systems are needed. The work of [18] investigated the secure transmission of a WEH relaying networks via analyzing the secrecy outage probability (SOP) and secrecy throughput in a delay-limited mode. The works of [19] considered a downlink NOMA system containing several EH receivers that can wiretap confidential information.…”