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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.

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In this paper, we evaluate outage probability (OP) of a cluster-based multi-hop protocol operating on an underlay cognitive radio (CR) mode. The primary network consists of multiple independent transmit/receive pairs, and the primary transmitters seriously cause co-channel interference (CCI) to the secondary receivers. To improve the outage performance for the secondary network under the joint impact of the CCI and hardware imperfection, we employ the best relay selection at each hop. Moreover, the destination is equipped with multiple antennas and uses the selection combining (SC) technique to enhance the reliability of the data transmission at the last hop. For performance evaluation, we first derive an exact formula of OP for the primary network which is used to calculate the transmit power of the secondary transmitters. Next, an exact closed-form expression of the end-to-end OP for the secondary network is derived over Rayleigh fading channels. We then perform Monte-Carlo simulations to validate the derivations. The results present that the CCI caused by the primary operations significantly impacts on the outage performance of the secondary network.

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In this paper, we analyze the tradeoff between outage probability (OP) and intercept probability (IP) for a multi-hop relaying scheme in cognitive radio (CR) networks. In the proposed protocol, a multi-antenna primary transmitter (PT) communicates with a multi-antenna primary receiver (PR), using transmit antenna selection (TAS) / selection combining (SC) technique, while a secondary source attempts to transmit its data to a secondary destination via a multi-hop approach in presence of a secondary eavesdropper. The secondary transmitters such as source and relays have to adjust their transmit power to satisfy total interference constraint given by PR. We consider an asymmetric fading channel model, where the secondary channels are Rician fading, while the remaining ones experience the Rayleigh fading. Moreover, an optimal interference allocation method is proposed to minimize OP of the primary network. For the secondary network, we derive exact expressions of end-to-end OP and IP which are verified by Monte Carlo simulations. KEYWORDSasymmetric fading channels, cognitive radio, multi-hop relaying protocol, security-reliability analysis Int J Commun Syst. 2019;32:e3854.wileyonlinelibrary.com/journal/dac dual-hop asymmetric fading channels. In, 14-17 multi-hop CR scenarios were studied, where the secondary source has to transfer information via several intermediate hops to the secondary destination.Recently, physical layer security (PLS) 18-20 has gained much attention of researchers. The PLS mechanism exploits physical channel characteristics (ie, random and noisy nature of wireless channels) in order to prevent the eavesdropper from intercepting transmission messages on wireless medium. Performance of the PLS-based systems is conventionally evaluated via average secrecy capacity (ASC), secrecy outage probability (SOP), and probability of non-zero secrecy capacity (PNSC). In, 21-23 security-reliability tradeoffs for secure communication systems were investigated, where the security and reliability are quantified in terms of intercept probability (IP) by an eavesdropper and the outage probability (OP), and by an intended receiver, respectively. In, 24 the authors proposed an opportunistic relay selection method to enhance the trade-off between security and reliability for random dual-hop CR networks. The authors of 25 evaluated the security-reliability tradeoff for energy-harvesting underlay CRs system, where cognitive base stations can harvest energy from their surrounding environments for the data transmission. In, 26-29 the authors investigated performances of secure multi-hop relaying networks. In the cooperative relaying approaches, the authorized transmitters often use randomize-and-forward (RF) technique 30,31 to randomly generate codebook so that the eavesdropper cannot combine the transmitted data with maximal ratio combining (MRC).Until now, almost published works related to the security versus reliability study have considered one-hop or dual-hop relaying networks. Motivated by this, we propose a novel m...

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