The authors study the secure transmission design in random cognitive radio networks where the primary users, the secondary users and the eavesdroppers are randomly distributed according to Poisson point processes. Centring on this scenario, the authors propose a simple and decentralised secure transmission scheme by jointly incorporating the secrecy guard zone and artificial noise. In particular, this transmission scheme helps to enhance secrecy performance via differentiating between secondary transmitters in accordance with the eavesdropping environment. They then analyse the connection outage and secrecy outage performance of the secondary network, based on which they obtain the closed‐form expression of the secrecy throughput. They further determine the optimal transmission power of the secondary transmitters and the optimal power allocation between the information‐bearing signal and artificial noise to maximise the secrecy throughput of the secondary network under primary and secondary outage constraints. The authors’ analysis highlights that introducing secrecy guard zone provides better security performance, and artificial noise performs as additional interference to insert a control between the reliability and security. Numerical results show how the system parameters affect the achievable maximum secrecy throughput, the optimal transmission power and the optimal power allocation between the information‐bearing signal and the artificial noise.
The authors study the secure transmission design in random cognitive radio networks where the primary users, the secondary users and the eavesdroppers are randomly distributed according to Poisson point processes. Centring on this scenario, the authors propose a simple and decentralised secure transmission scheme by jointly incorporating the secrecy guard zone and artificial noise. In particular, this transmission scheme helps to enhance secrecy performance via differentiating between secondary transmitters in accordance with the eavesdropping environment. They then analyse the connection outage and secrecy outage performance of the secondary network, based on which they obtain the closed‐form expression of the secrecy throughput. They further determine the optimal transmission power of the secondary transmitters and the optimal power allocation between the information‐bearing signal and artificial noise to maximise the secrecy throughput of the secondary network under primary and secondary outage constraints. The authors’ analysis highlights that introducing secrecy guard zone provides better security performance, and artificial noise performs as additional interference to insert a control between the reliability and security. Numerical results show how the system parameters affect the achievable maximum secrecy throughput, the optimal transmission power and the optimal power allocation between the information‐bearing signal and the artificial noise.
This paper studies the physical layer security (PLS) in an underlay cognitive radio (CR) network. Under an interference constraint set by the primary user, we propose a secure transmission scheme from a secondary source to a secondary destination in the presence of spatially random eavesdroppers, the distribution of which is modeled as a homogeneous Possion point process (PPP). In addition to transmitting the message signal, the secondary source is allowed to use part of its power to transmit jamming signals in order to interfere the eavesdroppers. Assuming that the secondary destination has the knowledge of the jamming signals, we derive the closed-form expression for the connection outage probability and an easy-to-compute expression for the secrecy outage probability to characterize the reliability and the security performance, respectively. Moreover, we determine the optimal power allocation factor and wiretap code rates which maximize the secrecy throughput of the wiretap channel under secrecy outage probability constraint.
Aiming at the cognitive wireless network in which the primary user communication pairs, the secondary user communication pairs and the eavesdropping nodes are randomly distributed, this paper designs an opportunistic transmission scheme. According to the random geometry theory, the primary user communication pairs, the secondary user communication pairs and the eavesdropping nodes are modeled as a Poisson point process, and then under the condition that the channel estimation error of the primary channel exists and the channel state information of the eavesdropping channel is unknown, the closed expression of the system's secrecy outage probability, connection outage probability, and secrecy throughput is derived. Using the designed opportunistic transmission scheme, the expression of system secrecy throughput is further obtained under the constraints of connection outage probability and secrecy outage probability. Finally, under the requirements of security and reliability, aiming at maximizing the secrecy throughput, the optimal pilot length under the transmission scheme is obtained, and the optimal pilot length with the transmit power and block fading length is studied. The simulation results verify the correctness of the theoretical analysis and show that the gain of throughput is obviously improved after the pilot is added.
In this paper, we study physical layer security in an underlay cognitive radio (CR) network. We consider the problem of secure communication between a secondary transmitter-receiver pair in the presence of randomly distributed eavesdroppers under an interference constraint set by the primary user. For different channel knowledge assumptions at the transmitter, we design four transmission protocols to achieve the secure transmission in the CR network. We give a comprehensive performance analysis for each protocol in terms of transmission delay, security, reliability, and the overall secrecy throughput. Furthermore, we determine the optimal design parameter for each transmission protocol by solving the optimization problem of maximizing the secrecy throughput subject to both security and reliability constraints. Numerical results illustrate the performance comparison between different transmission protocols.
In this paper, we consider multiple-input single-output multi-eavesdropper cognitive radio networks (MISOME-CRNs), where a secondary user (SU) aims to transmit confidential information to a legitimate SU receiver in the presence of a primary user (PU) and a multi-antenna passive eavesdropper in fast fading environments. For this system setting, we study beamforming with artificial noise (AN) for the SU to achieve confidential communications. We consider designing an AN-assisted optimal beamforming scheme, denoted cognitive beamforming (CB), which maximizes the ergodic secrecy rate. Moreover, we propose two suboptimal beamforming schemes, namely, scaled beamforming (SB) and projected beamforming (PB). We develop an analytical framework to assess the performance of the proposed schemes in a unified manner. First, we analyze the achievable ergodic secrecy rate of the three schemes. Second, we derive the optimal power allocation for the information and AN signals that maximizes the achievable ergodic secrecy rate in the large-antenna regime. Third, we study the performance of the three schemes in terms of the secrecy outage probability. Using numerical simulations, we validate our analytical results and show that CB achieves the best performance among the three proposed schemes. In addition, we provide insights into the effect of various system parameters on the secrecy performance. In particular, we show that the interference threshold at the PU plays an important role in the beamforming design.
A simple scheme to guarantee zero secrecy outage in an overlay cognitive radio network is proposed with the aid of Artificial Noise (AN). The secrecy outage probability and the condition on the secrecy rates to achieve zero secrecy outage will be determined. Our scheme shows that the transmission between the transceivers will be secured toward the eavesdropper with zero outages. This means that the message can always be secured by a simple strategy of transmission with the aid of AN. The optimum power allocation to information obtained to achieve the maximum zero-outage secrecy throughput will be highlighted. Importantly, the resulting maximum secrecy throughput increases with increasing transmit power, which overcomes the limit of traditional secret transmissions.
In this paper, the secrecy outage performance of cognitive radio (CR) systems with simultaneous wireless information and power transfer (SWIPT) is investigated, in which non-colluding eavesdroppers (Eves) are randomly located in a 2-dimensional disk and artificial noise is added to safeguard the secrecy performance of the targeted information delivery in the secondary network. The secondary users coexist with primary users in the same bands while the secondary user transmitter (SU-TX) transmits confidential messages to a legitimate receiver (Bob) and energy to multiple energy-receivers (ERs) via the same radio frequency signals. Apart from harvesting energy, these ERs may act as Eves to overhear the confidential information only for Bob. SU-TX equipped with multiple antennas performs beamforming to Bob, which is equipped with multiple antennas and adopts selection combining (SC) scheme. To enhance the secure performance of the considered CR-SWIPT system, SU-TX adds artificial noise (AN) to the original signal designed for Bob according to the instantaneous channel state information (CSI) between SU-TX and Bob, where the artificial noise and original signals for Bob are orthogonal so that Bob can cancel this noise. On ERs’ side, the total received energy for harvesting is not degraded, and a lower signal-to-interference-plus-noise ratio for eavesdropping on the information between SU-TX and Bob is introduced. The approximated closed-form expression for the secrecy outage probability (SOP) is derived by using Gauss-Laguerre quadrature, as well as the asymptotic results are valid in the high signal to noise ratio region. Finally, Monte-Carlo simulations are presented to validate the correctness of the derived analytical results.