Dedicated Power Beacon Research Articles

Physical layer security in wireless sensors networks: secrecy outage probability analysis

ABSTRACT The secrecy performance of wireless networks powered up by a dedicated power beacon (PB) is addressed in this work. Particularly, the closed-form expression of the secrecy outage probability (SOP) under the presence of multiple eavesdroppers is given. The considered networks are asymmetric since there are multiple eavesdroppers but only a single legitimate receiver. As a consequence, two wiretap schemes are employed, namely, non-colluding and colluding schemes, to take advantage of multiple eavesdroppers. To draw insights from the derived framework, the asymptotic framework of the SOP under the high transmit power regime is also provided. Next, Monte Carlo simulations are provided to validate the theoretical foundations of the proposed approach. Our findings show that by increasing the transmit power from −10 dB to 30 dB, the SOP ameliorates almost a thousand times. Additionally, the SOP is a monotonic decreasing function with a time-switching ratio. We also make comparisons with work in the literature in which the full-duplex relay is employed to help the legitimate link. Numerical results illustrate that the proposed network outperforms those described in the literature. Particularly, through reliance on the setup, the SOP under the proposed system is better than those of the literature by about twofold.

Age of information analysis for internet of things information status update system with cellular backhaul and dedicated energy harvesting beacons

SummaryThe Internet of Things (IoT) that is usually deployed with the assistance of cellular backhaul and energy harvesting (EH) is characterized by the status update freshness. However, the traditional nature EH results in the loss of information freshness due to the randomness of nature energy process. Although using wireless energy transferring (WET) to charge sensors can overcome this problem, this method has low‐energy efficiency. With these considerations, this paper proposes a novel IoT system under cellular communication scenario by simultaneously exploiting the nature EH and WET. The proposed IoT system is consisted of a cellular backhaul subsystem, a wireless EH and transferring (WEHT) subsystem, and a wireless sensor status update subsystem. The WEHT subsystem employs the dedicated power beacons harvesting energy from natural energy source and transferring the harvested energy to sensor. For the proposed IoT system, this paper first investigates the WEHT subsystem and constructs the Markov Chain (MC) of discrete energy states as well as the MC state transition matrix. Second, the average AoI and peak AoI (PAoI) are formulated by separately considering cellular backhaul and EHTBs. The AoI (PAoI) comparison shows that the proposed EHTB‐based IoT system can outperform the conventional non‐EHTB one where the sensor directly harvests energy from natural source. At the same time, the numerical results exploit the impact of system parameters on AoI and PAoI, respectively. It is found that there exists a trade‐off between the nature energy arrival and EHTB energy transfer so that the average minimum AoI and PAoI are achieved.

Performance Analysis of Dual-Hop AF Relaying with Non-Linear/Linear Energy Harvesting.

Massive device-to-device communication nodes and Internet of Things (IoT) devices are expected to be crucial components in next-generation wireless networks. However, the energy constraint of these nodes presents a challenge since the energy of the batteries is limited. Motivated by this, radio frequency energy harvesting (EH) has been developed as an efficient strategy to overcome the energy constraint of IoT devices and sensor networks. In this paper, a wireless-powered dual-hop amplify-and-forward relaying system, in the absence of a direct link between the source (S) and the destination (D), is considered. It is assumed that a dedicated power beacon (PB) transmits an energy-bearing signal from which the power-constrained S and relay (R) harvest energy. Theoretical derivations of bit error probability, outage probability, and throughput expressions are performed for both linear and non-linear energy harvesting models. Moreover, the theoretical results provided for different system parameters are validated via Monte Carlo simulations. The obtained results reveal the difference between the realistic non-linear EH model and the conventional linear EH model, which overestimates the system performance at high levels of harvested energy. Thus, it leads to misunderstanding the real performance of the EH systems. However, at low levels of harvested energy, both models behave similarly and provide realistic results.

New Practical Nonlinear Energy-Harvesting Models for Wireless-Powered Communications

As a massive number of nodes are expected to be connected to each other in next-generation wireless networks, the power supply of such multiple-antenna nodes is a challenge and requires new and sustainable solutions. Radio frequency energy harvesting (EH) is among the promising approaches to solve this issue. In this paper, two new mathematically tractable nonlinear EH (NL-EH) models are proposed, for which the system performance is evaluated in terms of average harvested power, throughput, and bit error probability. The system consists of one multiantenna power-constraint source harvesting its power from a dedicated power beacon and transmitting its signal to a destination equipped with multiple antennas. For a comprehensive analysis of the system, closed-form expressions are derived for Nakagami- m fading channels and the special case of Rayleigh channels. For comparison purposes, the performance derivations in Nakagami- m fading channels are provided for linear and piece-wise linear EH models given in the literature. Besides, the simulation results are obtained by applying the Monte-Carlo method for NL-EH models existing in the literature. The results provide a broadening view of EH systems and thoroughly compare the proposed NL-EH models with linear, piece-wise linear, and NL-EH models available in the literature. Hence, these provide better insights towards the analyses and design of EH systems.

Outage Performance of Underlay Multihop Cognitive Relay Networks with the use of the highest Power Beacon among Power Beacons

This paper studies the outage performance of multihop cognitive relay networks with energy harvesting in underlay paradigms, wherein the secondary users are powered by a dedicated power beacon (PB) have the highest energy level among their power beacons and the interference constrain from the

PERFORMANCE ANALYSIS IN WIRELESS POWERED D2D- AIDED NON-ORTHOGONAL MULTIPLE ACCESS NETWORKS

This paper examine how to integrate energy harvesting (EH) to non-orthogonal multiple access (NOMA) networks. Recently, device-to-device (D2D) underlaying licensed network is introduced as novel transmission mode to perform two nearby user equipment units (UEs) communicating directly without signal processing through the nearest base station (BS). By wireless power transfer, they can be further operational to D2D communications in which a UE may harvest energy from RF signal of dedicated power beacons (PB) to help EH assisted UEs communicate with each other or assist these UEs to communicate with the BS. In particular, we investigate outage and throughput performance in a scenario of D2D communications powered by RF signal where one UE may help other two UEs to exchange information with optimal throughput.

On secrecy performance for IoT enabled SWIPT multi-relaying NOMA systems

In this paper, we evaluate the secrecy performance in terms of secrecy outage probability (SOP) for Internet of things (IoT) enabled multi-relaying non-orthogonal multiple access (NOMA) networks with energy harvesting over Nakagami-m fading channels. Specifically, we consider the scenario that a power-constrained source and N(N⩾1) IoT relays first harvest energy from a dedicated power beacon under a time switching mode, and then the source sends a confidential information to a legitimate user via a selected IoT relay, which forwards the decoded signal together with its own information data under a NOMA protocol to two legitimate users in the presence of an eavesdropper. Moreover, a two-stage relay selection criterion is also adopted to enhance the system’s secrecy performance. As a benchmark, we also adopt a random relay selection scheme to analyze the secrecy performance. To clearly reveal the benefits of our proposed schemes, the analytical expressions for SOP under those two schemes have been obtained and validated through Monte-Carlo simulations.

Short-Packet Communications in Wireless-Powered Cognitive IoT Networks: Performance Analysis and Deep Learning Evaluation

In this paper, we study short-packet communications in wireless-powered cognitive Internet-of-Things (IoT) networks with multiple primary receivers (PRs). The considered system can be applied for small factory automations, where a source and multiple relays harvest energy from a multi-antenna dedicated power beacon (PB) to send short packets to a robot destination for controlling purposes under cognitive radio constraint imposed by PRs. We propose an opportunistic relay selection (ORS) scheme to maximize the end-to-end signal-to-noise ratio in cognitive IoT systems. Closed-form expressions for the average block error rate (BLER) of the proposed system are obtained, based on which the performance floor analysis, goodput, and energy efficiency (EE) are also carried out. Relying on analytical results, we develop a deep learning framework for the BLER prediction with high accuracy and short execution time. Simulation results show the BLER, goodput, and EE improvements of the ORS scheme over conventional relay selection schemes. Moreover, the developed deep learning-based evaluation model achieves the equivalent performance as the ORS scheme in terms of BLER, goodput, and EE, while remarkably reducing the execution time in cognitive IoT systems.

Harvesting Devices’ Heterogeneous Energy Profiles and QoS Requirements in IoT: WPT-NOMA vs BAC-NOMA

The next generation Internet of Things (IoT) exhibits a unique feature that IoT devices have different energy profiles and quality of service (QoS) requirements. In this paper, two energy and spectrally efficient transmission strategies, namely wireless power transfer assisted non-orthogonal multiple access (WPT-NOMA) and backscatter communication (Back-Com) assisted NOMA (BAC-NOMA), are proposed by utilizing this feature of IoT and employing spectrum and energy cooperation among the devices. In particular, the use of NOMA ensures that the devices with different QoS requirements can share the same spectrum, and WPT and Back-Com are employed to utilize the cooperation among the devices with different energy profiles, which avoids the use of a dedicated power beacon. Furthermore, for the proposed WPT-NOMA scheme, the application of hybrid successive interference cancelation (SIC) decoding order is also considered, and analytical results are developed to demonstrate that WPT-NOMA can avoid outage probability error floors and realize the full diversity gain. Unlike WPT-NOMA, BAC-NOMA suffers from an outage probability error floor, and the asymptotic behavior of this error floor is analyzed in the paper by applying the extreme value theory. In addition, the effect of a unique feature of BAC-NOMA, i.e., employing one device's signal as the carrier signal for another device, is studied, and its impact on the diversity gain is revealed. Simulation results are also provided to compare the performance of the proposed strategies and verify the developed analytical results.

Secrecy outage performance of multi-hop LEACH networks using power beacon aided cooperative jamming with jammer selection methods

In this paper, we evaluate secrecy performance of cooperative jamming (CJ) aided secure transmission for Multi-hop Low-Energy Adaptive Clustering Hierarchy (M-LEACH) networks, where data transmission between a source and a destination is performed via cluster heads (CHs) of intermediate clusters, and is overheard by an eavesdropper. To protect the source information at each hop, each CH selects one or many cluster nodes to realize the CJ technique. We propose energy harvesting (EH) based jammer selection methods named MAX-EH, MAX-IP and ALL-CJ, where the selected jammer(s) has to harvest wireless energy from a dedicated power beacon to generate jamming noises. In MAX-EH, the cluster node obtained the MAXimum Energy Harvested from the power beacon is chosen. In MAX-IP, the selected jammer is the cluster node providing the MAXimum Interference Power to the eavesdropper. In ALL-CJ, ALL cluster nodes in the clusters take part in the CJ operation. For performance evaluation, we derive expressions of the end-to-end (e2e) secrecy outage probability (SOP) for the proposed methods over Rayleigh fading channels. We then perform Monte-Carlo based computer simulations to verify the theoretical results. The results presented that the proposed methods outperform the RANDom jammer selection (RAND) and the corresponding method WithOut using the CJ technique (WO-CJ).

On the Performance of Multihop Cognitive Wireless Powered D2D Communications in WSNs

This paper studies the performance of multi-hop cognitive wireless powered device-to-device (D2D) communications in wireless sensor networks (WSNs). In our analysis, each sensor node harvests energy from multiple dedicated power beacons and shares the spectrum resources with multiple primary receivers (PRs) using underlay cognitive radio. Additionally, we consider a practical scenario of cognitive wireless powered D2D communications in WSNs, where the knowledge of interference channels is assumed to be imperfect. To improve the network performance, we propose two user scheduling schemes, namely dual-hop scheduling (DHS) and best-path scheduling (BPS) schemes. We then investigate the performance of the proposed scheduling schemes in terms of outage probability and outage floor. Through numerical results, we show that BPS scheme significantly outperforms DHS scheme, which in turns outperforms the state-of-the-art solution. Moreover, the advantages and drawbacks of each scheme are analyzed and discussed comprehensively. We also point out that the inaccurate knowledge of the interference channels significantly affects any performance metric of multi-hop cognitive D2D communications in WSNs such as outage probability, outage floor, and performance loss.

Power and Location Optimization of Full-Duplex Relay for Proactive Eavesdropping Networks

This work investigates the proactive eavesdropping through a friendly full-duplex (FD) relay and a legitimate monitor over the wireless-powered suspicious communication network, where one suspect source performs energy harvesting (EH) from one dedicated power beacon and then communicates with one suspect destination. Under this setup, a relay-aided proactive eavesdropping scheme is designed to improve the surveillance performance of the system. The closed-form expressions are derived under linear and nonlinear EH models, including the decoding outage probability for the suspicious link, the eavesdropping outage probability for the eavesdropping link, and the average eavesdropping rate (AER). Based on these obtained expressions, an optimization problem to maximize the AER is formulated by jointly optimizing the power and location of the relay. The existence of the optimal solution is carefully analyzed. Moreover, the separate optimization issues of the power and location are first established, and then a bisection-based searching algorithm is presented for the joint optimization problem with the linear EH model. Furthermore, to reduce the complexity of joint optimization, a low-complexity learning-based iteration algorithm is further proposed by employing the well-fitting characteristic of the deep feedforward neural network. Numerical results verify the effectiveness of the proposed algorithm, and show that the optimized FD relay-aided proactive eavesdropping scheme outperforms the reference schemes. Finally, the application scenarios of the proposed proactive eavesdropping scheme are discussed.

Wireless-Powered Communication Networks With Random Mobility

In this paper, we consider a wireless-powered communication network (WPCN), where an energy-limited multi-antenna information source, powered by a dedicated power beacon, communicates with a mobile user (MU). The MU is equipped with a single-antenna and its mobility is characterized by the well-known random waypoint mobility model. To gain the advantages with the use of multiple antennas at the source, we adopt two popular multiple-antenna transmission schemes, namely maximal-ratio transmission (MRT) and transmit antenna selection (TAS). Differently from previous works which considered only static scenarios, this paper aims to investigate wireless power and information transfer in the scenario with a random mobile user under Nakagami-$m$ fading. It is noteworthy that a special case of our analysis, i.e., the Rayleigh fading case, has not been examined in the literature as well, which enhances the contribution value of the proposed analysis. Considering both MRT and TAS schemes, closed-form expressions for the outage probability, average delay-limit throughput, average delay-tolerant throughput, average bit error rate (BER), and throughput under average BER constraint are derived. The analysis quantifies the impact of the mobility and propagation environments, which are characterized by the path-loss exponent and multipath parameter for the PB-AP link and AP-MU link, on the performance of a WPCN. The analytical results are compared with Monte-Carlo simulations in order to validate the analysis and provide useful insights on the impact of different parameters on the system performance.

Relaying Protocols and Delay Analysis for Buffer-aided Wireless Powered Cooperative Communication Networks

In this paper, we investigate a buffer-aided wireless powered cooperative communication network (WPCCN), in which the source and relay harvest the energy from a dedicated power beacon via wireless energy transfer, then the source transmits the data to the destination through the relay. Both the source and relay are equipped with an energy buffer to store the harvested energy in the energy transfer stage. In addition, the relay is equipped with a data buffer and can temporarily store the received information. Considering the buffer-aided WPCCN, we propose two buffer-aided relaying protocols, which named as the buffer-aided harvest-then-transmit (HtT) protocol and the buffer-aided joint mode selection and power allocation (JMSPA) protocol, respectively. For the buffer-aided HtT protocol, the time-averaged achievable rate is obtained in closed form. For the buffer-aided JMSPA protocol, the optimal adaptive mode selection scheme and power allocation scheme, which jointly maximize the time-averaged throughput of system, are obtained by employing the Lyapunov optimization theory. Furthermore, we drive the theoretical bounds on the time-averaged achievable rate and time-averaged delay, then present the throughput-delay tradeoff achieved by the joint JMSPA protocol. Simulation results validate the throughput performance gain of the proposed buffer-aided relaying protocols and verify the theoretical analysis.

Throughput analysis of wireless-powered decode-and-forward relay systems with interference

This paper investigates the throughput of a wireless-powered dual-hop relaying system with the presence of co-channel interference. Specifically, an energy-constrained source node communicates with a destination node through an energy-constrained decode-and-forward relay node. Considering a time-splitting approach, both source and relay are first powered by a dedicated power beacon (PB), whereas the relay further exploit the benefit from the interfering signals as a plentiful power supply. Then, source transmits information to the destination with the help of the relay. The instantaneous throughput of the system is maximized by optimizing the time-split parameter. In order to determine the average throughput of the system in delay-limited transmission mode, analytical expressions for the outage probability are derived. In addition, we present asymptotic outage expressions under strong interference conditions. Our results, reveal that by energy harvesting from the interfering signals at the relay, the instantaneous throughput is increased compared with the case where the relay is only powered by the PB. Moreover, under strong interference conditions the optimal time-split that maximize the throughput of the the delay-limited transmission mode is much higher than that for weak interference condition.

A New Interweave Cognitive Radio Scheme for Out-Band Energy Harvesting Systems

In this paper, a new interweave cognitive radio (CR) transmission scheme is analytically presented for energy harvesting (EH)-enabled transmitting nodes. The EH is performed via a dedicated power beacon (PB) base station through wireless power transfer, which harvests energy to both primary and secondary systems. The out-band mode-of-operation between PB and the two heterogeneous systems is considered, i.e., data communication and EH are realized at different frequency bands and asymmetric (non-equal) time durations. The performance of the new interweave CR system is studied under independent and not necessarily identically distributed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\kappa -\mu $ </tex-math></inline-formula> shadowed faded channels. Representative numerical and simulation results corroborate the effectiveness of the proposed scheme and presented analysis, while some useful engineering insights are provided.

On the Capacity of Wireless Powered Communication Systems Over Rician Fading Channels

In this paper, we consider a point-to-point multi-input multi-output wireless-powered communication system, where the source S is powered by a dedicated power beacon (PB) with multiple antennas. Employing the time splitting protocol, the energy constrained source S first harvests energy through the radio-frequency signals sent by the PB and then uses this energy to transmit information to the destination D. Unlike several prior works, we assume that the energy transfer link is subjected to Rician fading, which is a real fading environment, due to relatively short range power transfer distance and the existence of a strong line of sight path. We present a comprehensive analysis of the achievable ergodic capacity in two scenarios, depending on the availability of channel state information (CSI) at PB, namely, the absence of CSI and partial CSI . For the former case, equal power allocation is used, while for the later one, energy beamforming is used to enhance the energy transfer efficiency. For both the cases, closed-form expressions for the upper and lower bounds of the ergodic capacity are derived. Furthermore, the optimal time split is discussed, and the capacity in the low and high signal-to-noise ratio regimes is studied through simple closed-form expressions. Numerical results and simulations are provided to validate the theoretical analysis. The results show that the Rician factor $K$ has a significant impact on the ergodic capacity performance, and this impact strongly depends on the availability of the CSI at the PB.

Secrecy Performance of Wireless Powered Communication Networks With Multiple Eavesdroppers and Outdated CSI

In this paper, we present a comprehensive secrecy performance analysis of wireless powered communication networks with multiple eavesdroppers, where an energy-limited information source with multiple antennas harvests the radio frequency energy from a dedicated power beacon (PB) before transmission. To exploit the benefits of multiple antennas at source, two popular multi-antenna transmission schemes, i.e., maximal ratio transmission and transmit antenna selection, are investigated for two intercepting ways at Eves, i.e., non-colluding and colluding scenarios, respectively. Specifically, adopting the time-switching protocol at PB, we derive exact closed-form expressions of the secrecy outage probability and the average secrecy rate for both two transmission schemes taking into account the outdated channel state information. Furthermore, in order to deeply extract insights on the system design, we further present tractable asymptotic secrecy outage probability and ergodic secrecy capacity at high signal-to-noise ratio regimes, which easily enable us to obtain the secrecy diversity order and coding gain of two transmission schemes, respectively. From our analysis, several important concluding remarks are obtained as follows: 1) full secrecy diversity order can be achieved by both two transmission schemes with no feedback delay, however, it reduces to one in the presence of feedback delay; 2) as the number of eavesdroppers increases, the secrecy performance gap between non-colluding and colluding scenarios becomes large; and 3) maximal ratio transmission (MRT) scheme always outperforms transmit antenna selection (TAS) scheme with no feedback delay. However, TAS scheme achieves a similar performance as MRT scheme or even better in moderate and even serious feedback delay conditions.

Performance Analysis of Wireless Powered Communications With Multiple Antennas

This paper analytically investigates the performance of a wireless powered communication system, where a source powered by multiple dedicated power beacons communicates with a destination. Specifically, we consider a harvest-then-transmit multiple-input multiple-output communication system, where the source uses all harvested energy for information transmission in each time block. The random placement of terminals is characterized by stochastic geometry tools. Taking into account the effects of imperfect channel state information in wireless energy transfer and wireless information transmission, the ergodic achievable rate of information transmission is derived analytically by considering co-channel interference (CCI) and the noise. In addition, assuming the CCI can be accurately approximated by a Gamma distributed variable, the outage probability of information transmission is investigated. Numerical results validate the analytical results and show the impacts of the antenna number, distribution density, estimation error, and the transmit power of terminals on the system performance.

Improving Secrecy Performance of a Wirelessly Powered Network

This paper considers the secrecy communication of a wirelessly powered network, where an energy-constrained legitimate transmitter (Alice) sends message to a legitimate receiver (Bob) with the energy harvested from a dedicated power beacon, while an eavesdropper (Eve) intends to intercept the information. A simple time-switching protocol with a time-switching ratio $\alpha $ is used to supply power for the energy-constrained legitimate transmitter. To improve the physical layer security, we first propose a protocol that combines maximum ratio transmission with zero-forcing (ZF) jamming for the case without Eve’s channel state information (CSI), i.e., Alice has access to Bob’s CSI only. Then, we propose a protocol that uses a ZF transmitting strategy to minimize the signal-to-noise ratio (SNR) at Eve for the case that Alice is capable of obtaining partial CSI related to Eve. Closed-form expressions and simple approximations of the connection outage probability and secrecy outage probability are derived for both protocols. Furthermore, the secrecy throughput as well as the diversity orders achieved by our proposed protocols are characterized, and the optimal time-switching ratio $\alpha $ and power allocation coefficient $\beta $ for secrecy throughput maximization are derived in the high SNR regime. Finally, numerical results validate the effectiveness of the proposed schemes.