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This paper investigates a novel full-duplex (FD) simultaneous wireless information and power transfer (SWIPT) based cooperative non-orthogonal multiple access (FDS-NOMA) system, where far distant NOMA IoT users are helped by the NOMA strong user with the capability of energy harvesting (EH) and FD communications. The downlink (DL-NOMA) principle is used to transmit the superimposed signals from source i.e a base station (BS) to an energy-limited FD relay where relay harvests energy from the transmit power of the BS. The relay after detecting the superimposed signals using successive interference cancellation (SIC), retransmits the decoded signals using superposition coding to the IoT users. We derive the analytical expressions of the outage probability and ergodic rates experienced by the NOMA strong user as well as NOMA IoT users. The results shows that proposed cooperative NOMA scheme can be used to serve IoT users using EH relay. Extensive simulations are performed to verify the accuracy of the derived approximate closed-from expressions. [ABSTRACT FROM AUTHOR]

Physical layer security in relay based cooperative networks is a promising approach to maintain confidentiality of information. In this paper, secrecy performance of a dual hop network, with multiple energy harvesting decode and forward (DF) relays, has been analyzed where an eavesdropper also receives the information from the transmission of a selected relay. A selected DF relay harvests energy based on power splitting (PS) scheme in the first time slot. In the second time slot, the selected DF relay transmits the information as well as jamming signals, only when it has harvested sufficient power as decided by a threshold, based on the outage constraint of the network. The secrecy outage probability (SOP) under some assumed conditions, termed as a conditional SOP (CSOP), has been evaluated in closed form. Performance regarding the CSOP increases with increase in transmits power of the source, threshold outage rate, number of relay and energy conversion efficiency, whereas it decreases with an increase in threshold secrecy rate. We indicate the optimal value of PS factor for harvesting energy and the optimal value of a fraction of harvested energy devoted to information signal transmission at which the CSOP is minimum. The SOP without any condition has also been evaluated with and without jamming. The results shows that the CSOP yields better results than the SOP. It is observed that the CSOP with jamming is better than the SOP with jamming by 49.12% for 1 bits/s/Hz threshold secrecy rate and by 81.94% for a threshold secrecy rate of 0.5 bits/s/Hz, respectively at 10 dBW of the source transmits power. A MATLAB based simulation is used to verify our analytical works of the CSOP and the SOP with jamming. [ABSTRACT FROM AUTHOR]

In this paper, we evaluate the secrecy outage performance and throughput of a hybrid cognitive radio network, where a secondary user (SU) accesses the primary spectrum either in underlay or overlay mode based on spectrum sensing decision. In underlay, the transmit power of the SU as well as the relay is limited by the maximum acceptable interference at primary user (PU) receiver as required by an PU outage constraint, a quality of service for PU. The secondary network employs a decode and forward relay which harvests energy from the radio frequency signal of SU following a time switching relaying protocol. We develop analytical expressions for secrecy outage considering the impact of sensing decision and sensing time. Impact of sensing time, imperfect channel state information of interfering link, energy harvesting time, acceptable interference threshold and PU outage constraint on the secrecy outage probability, as well as throughput of SU are investigated. Further, an interplay between throughput performance and secrecy outage of the network is highlighted. [ABSTRACT FROM AUTHOR]

This paper studies the achievable total throughput of an energy harvesting cooperative cognitive radio (CR) network. A CR transmitter cooperates with a primary user (PU) transmission if PU is found to be present in the given channel while it transmits its own data in the absence of PU. The CR transmitter is an energy harvesting node which harvests simultaneously from non-RF signal as well as RF signal of PU. The CR transmitter uses the harvested energy on shared basis for cooperation and transmission. The same study is also extended for cooperation of multiple CRs in multiple PU band scenario. In cooperation in muti-band scenario, all CRs sense all PU channels and sensing informations are fused at fusion centre to know about the status of PU. Performance is investigated in terms of total network throughput for several parameters such as sensing time, energy splitting parameter, and energy allocation ratio etc. Novel analytical expressions for total useful throughput and optimal energy allocation ratio parameter under the considered network scenario are developed. Useful throughput and optimal energy allocation ratio parameter are also estimated for a target secondary network (CR network) throughput under a quality of service constraint of PU such as collision probability. It is observed that the value of optimal energy allocation parameter gets reduced if the number of CRs in cooperation increases or the number of PU channels increases. [ABSTRACT FROM AUTHOR]

Cooperative spectrum sensing (CSS) is an efficient method to detect vacant spectrum of a primary user (PU) by combining sensing information of multiple cognitive radios (CRs) in presence of fading. In this paper, effects of perfect and imperfect channel state information (CSI) on CSS network is evaluated. The proposed network is operated over Nakagami-q (Hoyt) and Nakagami-n (Rician) fading affecting both reporting (R) and sensing (S) channels. The CRs which employ energy detectors (EDs) are selected on the basis of CSI between them and a fusion center (FC). The knowledge on the quality of R-channels is estimated at FC using a channel estimator. The estimated CSI is either perfect when there is no error in the estimator, or imperfect when errors are present. Accordingly, CRs are selected under both perfect CSI and imperfect CSI cases. All CRs use the decision statistics obtained by EDs and make one-bit binary decisions about the availability of a PU. Selected CRs only transmit decision information to the FC. The miss detection probability and error rate of network under two cases of selection are evaluated by operating majority and maximal ratio combining rules at the FC. Performance is analyzed for different channel and network parameters and comparison between fusion rules for different fading channels is also highlighted. [ABSTRACT FROM AUTHOR]

In this paper, the impact of a multi slot based cooperative spectrum sensing (CSS) on the performance of a cognitive radio (CR) network has been investigated. Each CR user, equipped with an improved energy detector (IED), uses a number of mini slots of the sensing time to perform the spectrum sensing. Each CR uses OR logic to combine the sub local decisions generated in each mini slot to obtain a local decision at CR level. Local decisions are sent to fusion centre (FC) over reporting channel. The FC obtains a final decision about the presence of primary user (PU) by combining the local decisions using a fusion rule: Majority or Maximal Ratio Combining. The performance of the CSS is assessed in terms of detection probability and false alarm probability considering both the sensing and reporting channels are Rayleigh faded. Furthermore, the impact of a number of sensing slots and IED parameter on throughput of CR network is also evaluated under the proposed spectrum sensing scenario. Impacts of several sensing parameters such as sensing channel SNR and reporting channel SNR on the performance of CR network are also evaluated. Performances of two fusion rules under study are compared. Effect of sensing error and synchronisation error is indicated. Further the study is extended for independent but non identically distributed (i.n.i.d.) Rayleigh faded channels as well as for a multiple PU scenario also. [ABSTRACT FROM AUTHOR]