Secrecy performance of TAS/SC-based multi-hop harvest-to-transmit cognitive WSNs under joint constraint of interference and hardware imperfection

In this paper, we evaluate the secrecy performance of multi-hop cognitive wireless sensor networks (WSNs). In the secondary network, a source transmits its data to a destination via the multi-hop relaying model using the transmit antenna selection (TAS)/selection combining (SC) technique at each hop, in the presence of an eavesdropper who wants to receive the data illegally. The secondary transmitters, including the source and intermediate relays, have to harvest energy from radio-frequency signals of a power beacon for transmitting the source data. Moreover, their transmit power must be adjusted to satisfy the quality of service (QoS) of the primary network. Under the joint impact of hardware imperfection and interference constraint, expressions for the transmit power for the secondary transmitters are derived. We also derive exact and asymptotic expressions of secrecy outage probability (SOP) and probability of non-zero secrecy capacity (PNSC) for the proposed protocol over Rayleigh fading channel. The derivations are then verified by Monte Carlo simulations.Web of Science195art. no. 116

Energy harvesting over Rician fading channel: A performance analysis for half-duplex bidirectional sensor networks under hardware impairments

In this paper, a rigorous analysis of the performance of time-switching energy harvesting strategy that is applied for a half-duplex bidirectional wireless sensor network with intermediate relay over a Rician fading channel is presented to provide the exact-form expressions of the outage probability, achievable throughput and the symbol-error-rate (SER) of the system under the hardware impairment condition. Using the proposed probabilistic models for wireless channels between mobile nodes as well as for the hardware noises, we derive the outage probability of the system, and then the throughput and SER can be obtained as a result. Both exact analysis and asymptotic analysis at high signal-power-to-noise-ratio regime are provided. Monte Carlo simulation is also conducted to verify the analysis. This work confirms the effectiveness of energy harvesting applied in wireless sensor networks over a Rician fading channel, and can provide an insightful understanding about the effect of various parameters on the system performance.Web of Science186art. no. 1781

Time-slot based architecture for power beam-assisted relay techniques in CR-WSNs with transceiver hardware inadequacies

Over the past two decades, numerous research projects have concentrated on cognitive radio wireless sensor networks (CR-WSNs) and their benefits. To tackle the problem of energy and spectrum shortfall in CR-WSNs, this research proposes an underpinning decode-&-forward (DF) relaying technique. Using the suggested time-slot architecture (TSA), this technique harvests energy from a multi-antenna power beam (PB) and delivers source information to the target utilizing energy-constrained secondary source and relay nodes. The study considers three proposed relay selection schemes: enhanced hybrid partial relay selection (E-HPRS), conventional opportunistic relay selection (C-ORS), and leading opportunistic relay selection (L-ORS). We present evidence for the sustainability of the suggested methods by examining the outage probability (OP) and throughput (TPT) under multiple primary users (PUs). These systems leverage time switching (TS) receiver design to increase end-to-end performance while taking into account the maximum interference constraint and transceiver hardware inadequacies. In order to assess the efficacy of the proposed methods, we derive the exact and asymptotic closed-form equations for OP and TPT & develop an understanding to learn how they affect the overall performance all across the Rayleigh fading channel. The results show that OP of the L-ORS protocol is 16% better than C-ORS and 75% better than E-HPRS in terms of transmitting SNR. The OP of L-ORS is 30% better than C-ORS and 55% better than E-HPRS in terms of hardware inadequacies at the destination. The L-ORS technique outperforms C-ORS and E-HPRS in terms of TPT by 4% and 11%, respectively

Performance analysis for three cases of outage probability in one-way DF full-duplex relaying network with presence of direct link

In this paper, the one-way decode-and-forward (DF) full-duplex relaying network system with presence of direct link is investigated. In the analysis section, we derived the exact, lower, and upper bound for outage probability (OP) with maximal ratio combining (MRC) at the receiver. Furthermore, the system performance's analytical expressions are verified by using the Monte Carlo simulation. In addition, we investigated the effect of the main parameters on the OP of the proposed system. Finally, we can sate that the simulation curves overlap the analytical curves to convince the analysis section. This research can provide a novel recommendation for the communication network

Relaying in the Internet of Things (IoT): A Survey

The deployment of relays between Internet of Things (IoT) end devices and gateways can improve link quality. In cellular-based IoT, relays have the potential to reduce base station overload. The energy expended in single-hop long-range communication can be reduced if relays listen to transmissions of end devices and forward these observations to gateways. However, incorporating relays into IoT networks faces some challenges. IoT end devices are designed primarily for uplink communication of small-sized observations toward the network; hence, opportunistically using end devices as relays needs a redesign of both the medium access control (MAC) layer protocol of such end devices and possible addition of new communication interfaces. Additionally, the wake-up time of IoT end devices needs to be synchronized with that of the relays. For cellular-based IoT, the possibility of using infrastructure relays exists, and noncellular IoT networks can leverage the presence of mobile devices for relaying, for example, in remote healthcare. However, the latter presents problems of incentivizing relay participation and managing the mobility of relays. Furthermore, although relays can increase the lifetime of IoT networks, deploying relays implies the need for additional batteries to power them. This can erode the energy efficiency gain that relays offer. Therefore, designing relay-assisted IoT networks that provide acceptable trade-offs is key, and this goes beyond adding an extra transmit RF chain to a relay-enabled IoT end device. There has been increasing research interest in IoT relaying, as demonstrated in the available literature. Works that consider these issues are surveyed in this paper to provide insight into the state of the art, provide design insights for network designers and motivate future research directions

Transceiver design for wireless energy harvesting cooperative networks

In this thesis, the RF energy harvesting technique is studied in the cooperative wireless network, and different optimization studies are investigated. First, an energy-efficient optimization is considered in the cooperative system with the time switching relaying and power splitting relaying protocols. Then, a security issue in the cooperative network with energy harvesting is proposed, in which the optimization problem is designed to maximize the secrecy rate. We also consider the application of energy harvesting in the full-duplex relaying network with a self-energy recycling protocol. Finally, the energy harvesting is studied in the full-duplex cooperative cognitive radio network. The system performance of all studies is verified in the thesis with MATLAB simulation results

マルチホップ無線ネットワークの特性解析に関する研究

九州工業大学博士学位論文 学位記番号:情工博甲第309号 学位授与年月日:平成28年3月25日1 Introduction||2 Impact of Transceiver Hardware Impairments on Cognitive Network||3 Case study: Two-Way Cognitive Relay in RF Energy HarvestingWireless Sensor Network||4 Soft Information Relaying Protocol||5 Overall Conclusion and FutureWorkWireless communication has been considered as the most efficient mean of data transmission. We have been witnessed the breakthrough of wireless communication era in many manifolds, such as speech, coverage area, and stability. However, frequency bands, the resource to convey information wirelessly, are limited and expensive to be granted usage licenses. Attaining the goals of ubiquitous wireless devices will require the future wireless networks stepping forward to overcome the scarcity and expensiveness of wireless frequency bands. Thus, the future wireless networks should evolve to utilize wireless frequencies more efficiently, such as cognitive relay network where non-license users are able to transmit data in the same frequency band that officially allocated to primary users. Subsequently, the transmit power of users in a cognitive network is limited and the performance is vulnerable to impairments of transceiver hardware. This dissertation aims to analyze the performance of the cognitive relay network under the impact of transceiver hardware impairments. A case study of two-way cognitive relay network is given for further investigate the impact of transceiver hardware impairments on end-to-end outage performance and throughput. Furthermore, we provide a new relaying scheme in order to lessen the impact of transceiver hardware impairment and further boost the system performance. For the purposes, this dissertation is organized into five (5) chapters. Chapter 1: Introduction. In this chapter, multihop wireless networks and the performance metrics are overviewed. In particular, the relay networks and cognitive relay networks are presented. Moreover, the general model of the practical transceiver hardware impairment is detailed for further analysis. Chapter 2: The impact of transceiver hardware impairments on cognitive relay networks. By using the general hardware impairment model for the received signal, the closed forms of outage probability of the relay network with decode-and-forward (DF) and amplify-and-forward (AF) under the impact of transceiver hardware imperfection are derived. Based on these results, we provide further discussion on transceiver hardware selection guideline. Chapter 3: Case study: two-way cognitive relaying in energy harvesting wireless sensor networks. A two-way relay wireless sensor network equipped with RF energy harvesting node is introduced. This network is aimed to be implemented in hazardous or remote areas where power supply for the relay node is difficult to maintain. In this chapter, we consider four configurations of the network with formed by combining two bidirectional relaying protocols and two wireless power transfer policies. The detailed performance analysis of outage probability and throughput of the case-study network with four configurations are presented. Based on the analysis, we provide performance comparison between the four and suggest the network configuration with the best performance. Chapter 4: Soft information relaying protocol. The soft information relaying protocol is proposed and analyzed. The analysis shows that this relaying protocol can gradually reduce the impact of transceiver hardware impairment on cognitive relay networks. Hence, soft relaying protocol is considered as a solution for cognitive relay network with cost-effective wireless transceiver devices. Chapter 5: Overall conclusion. An overall summary of the works presented in the above is provided in this chapter. Moreover, the future related work is also discussed. The results in this dissertation acknowledge the impact of transceiver hardware impairment by presenting the reduction of outage probability and throughput of the cognitive relay network. It puts forward the consideration of including the impact of transceiver hardware impairments on wireless network performance analysis, especially for the cognitive networks of which the transmit power is limited. Furthermore, a new relaying protocol, namely soft information relaying protocol, is proposed as a solution to lessen the impact of transceiver hardware impairment. The analysis shows that the impact of transceiver hardware impairment in cognitive relay network is reduced in compared to conventional relaying schemes. As a final point, we have provided a full picture of performance analysis for the cognitive relay network under the impact of transceiver hardware imperfection and the solution to reduce the performance loss by applying soft information relaying scheme. This research would contribute to boost the development of cognitive relay networks where frequency bands are used more efficiently

Energy Harvesting in Cooperative Communications

Ühiskommunikatsioon on võimalik meetod lahendamaks informatsiooni levimist juhtmeta võrgus mitmikteekonna korral. See võimaldab laiendada võrgu katvust ning pakkuda võimendust kasutades olemasolevat taristut. Praktikas tehakse seda kasutades sõlmpunkte vahereleedena. Nii mitmese ligipääsuga releede süsteem kui paralleelsete releede süsteem on võimalikud kandidaadid tulevastes juhtmeta ühisvõrkudes nende ülekandekiiruse efektiivsuse ning parema energiatarbe tõttu.\n\r\n\rVõimenda-ja-edasta (AF) ning dekodeeri-ja-edasta (DF) on peamised ühisreleede protokollid, mida kasutatakse üle releekanalite. Me uurime käesolevas magistritöös paralleelseid releesid AF ühiskommunikatsiooni võrkudes kasutades QPSK signaliseerimist üle Rayleigh’ kiirelt hajuva kanali koos valge aditiivse Gaussi müraga. Sihtkohas vastuvõetud signaali detekteerimiseks kasutades võrgus olevaid tegevuseta kasutatakse maksimaalse suhte ühendamise (MRC) meetodit. Mõõtes sihtkohast vastu võetud ühendsignaali sümbolite veasuhet (SER) arvutusliku simulatsiooni abil, uurime me suhet releede arvu ning kommunikatsiooni kvaliteedi vahel.\n\r\n\rSüsteemi energeetiline efektiivsus määrab selle operatsioonilise jätkusuutlikkuse. Energiakogumise (EH) meetod on hädavajalik tehnoloogia juhtmeta süsteemides, kus on piiratud ligipääs usaldusväärsele elektritoitele ja laadimisvõimalustele. Käesolevas magistritöös uurime me mitmese ligipääsuga releede süsteeme kasutades EHtehnoloogiat. Me eeldame, et lähte- ja releesõlmedel pole ühendatud energiaallikat, kuid on taaslaetav energiatalletus. Seega, iga sõlme käivitatakse ligipääsupunkti (AP) edastatud raadiosignaalidelt kogutud energiast ning iga sõlm toimib salvesta-siis- koostööta (STC) režiimis. Me simuleerime arvutuslikult ühendusetaseme jõudlust kasutades füüsilise ühenduse võrgukodeerimist EHja DF protokolli olemasolul. Käesolev magistritöö esitab erinevaid energiakogumise meetodeid (EH ja STC) ning nende katkemistõenäosusi. Esitatud skeemid saavutavad SER jõudluse, mis läheneb püsiva toiteallikaga jõudlusele ning laiendab oluliselt süsteemi energiapüsivust, samas säilitades pidevat läbilaskejõudlust.Cooperative communications is a promising technique used to combat the multipath propagation in wireless networks. It can also extend the network coverage and provide the diversity gain by using the existing infrastructure. In practice, this is often achieved by using idle nodes in the network as relays. The multiple access relay system and parallel relay system are appealing candidates for emerging wireless cooperative networks due to bandwidth efficiency and improved power consumption.\n\r\n\rThe amplify and forward (AF) and decode and forwards (DF) protocols are basic cooperative relay protocols used over the relay channels. In this thesis, we study parallel relays in AF cooperative communication networks using QPSK signalling over the Rayleigh fast fading with additive Gaussian noise channels. The maximum ratio combining (MRC) method is employed to detect the received signals at the destination. By simulating the symbol error rate (SER) of the combined received signal at the destination, we study a trade-off between the number of relays and the quality of the communications. \n\r\n\rThe energy efficiency of a system determines its operational sustainability. Energy harvesting (EH) is a crucial technology for a variety of wireless systems that have limited access to a reliable electricity supply or recharging sources. In this thesis, the design of a multiple access relay system (MARS) using EH is considered. We assume that the sources and the relay have no embedded power supply but rechargeable energy storage devices. Thus, each node is powered by harvesting the energy from the RF signals broadcasted by an access point (AP), and it operates in store-then-cooperate (STC) mode. We simulate the link level performance by using the physical layer network coding in the presence of EH with DF protocol. The thesis presents energy harvesting schemes (EH and STC) and outage probability analysis. The schemes presented in this thesis achieve SER performance approaching that of a fixed power supply and contribute significantly to sustaining the energy in the system while maintaining a constant throughput