This paper designs a new chance transmission scheme for the cognitive wireless network with randomly distributed wiretap nodes. Under the condition that the channel estimation error exists at receiver and the channel information of the wiretap channel is unknown, the closed expression of the system's secrecy outage probability, connection outage probability and secrecy throughput is deduced. Based on these, we obtain the trade-off between the secrecy throughput and energy efficiency. Finally, under the requirement of security and reliability, the optimal pilot length and transmit power under the transmission scheme are obtained by maximizing the compromise function. The simulation results verify the correctness of the theoretical analysis and show that the gain of the net secrecy throughput is improved after adding the pilot. Considering the energy efficiency, the transmit power has an optimal value to maximize compromise function, and we obtain the expression of most superior power.
This paper designs a new chance transmission scheme for the cognitive wireless network with randomly distributed wiretap nodes. Under the condition that the channel estimation error exists at receiver and the channel information of the wiretap channel is unknown, the closed expression of the system's secrecy outage probability, connection outage probability and secrecy throughput is deduced. Based on these, we obtain the trade-off between the secrecy throughput and energy efficiency. Finally, under the requirement of security and reliability, the optimal pilot length and transmit power under the transmission scheme are obtained by maximizing the compromise function. The simulation results verify the correctness of the theoretical analysis and show that the gain of the net secrecy throughput is improved after adding the pilot. Considering the energy efficiency, the transmit power has an optimal value to maximize compromise function, and we obtain the expression of most superior power.
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.
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.
The simultaneous wireless information and power transfer (SWIPT) technique is regarded as a promising approach to enhance performance of wireless networks with limited energy supply. However, due to the broadcast nature of wireless radio, the energy receiver may act as a potential eavesdropper to eavesdrop the information sent to the information receiver. To address this issue, in this paper, we propose an optimization framework of the target secrecy rate and the power allocation ratio based on the secrecy outage probability and the effective secrecy throughput in the SWIPT system over fading wiretap channel. Moreover, we derive the closed-form expression of the secrecy outage probability and the effective secrecy throughput for two secrecy transmission modes. Furthermore, we formulate the effective secrecy throughput maximization problem under the reliability constraint in the on-off and adaptive transmission modes and provide the closed-form optimal solutions of the power allocation ratio and the target secrecy rate. Finally, we provide numerical results that give an insight into the effect of various system parameters on the secrecy outage probability and the effective secrecy throughput, such as the target secrecy rate, the power allocation ratio, and average gains of the main channel and the eavesdropper channel.
We propose a secure transmission scheme for a relay wiretap channel, where a source communicates with a destination via a decode-and- forward relay in the presence of spatially random- distributed eavesdroppers. We assume that the source is equipped with multiple antennas, whereas the relay, the destination, and the eavesdroppers are equipped with a single antenna each. In the proposed scheme, in addition to information signals, the source transmits artificial noise signals in order to confuse the eavesdroppers. With the target of maximizing the secrecy throughput of the relay wiretap channel, we derive a closed-form expression for the transmission outage probability and an easy-to-compute expression for the secrecy outage probability. Using these expressions, we determine the optimal power allocation factor and wiretap code rates that guarantee the maximum secrecy throughput, while satisfying a secrecy outage probability constraint. Furthermore, we examine the impact of source antenna number on the secrecy throughput, showing that adding extra transmit antennas at the source brings about a significant increase in the secrecy throughput.
This paper investigates a secure transmission in the multiple-input multiple-output (MIMO) cognitive wiretap networks, where a secondary transmitter (Alice) sends data to a secondary receiver (Bob) in the presence of an eavesdropper (Eve). In order to solve the problems of inter channel interference and inter antenna synchronization encountered by traditional MIMO technologies, the antenna transmission scheme is adopted at the transmitter. As a comparison, we design two different antenna transmission schemes, namely transmit antenna selection maximal-ratio combining (TAS-MRC) scheme and differential spatial modulation maximal-ratio combining (DSM-MRC) scheme, respectively. Moreover, due to outdated channel state information (CSI) of the interference link from Alice to the primary user (PU), we propose power control mechanism to protect the quality of service (QoS) of PU. Furthermore, the closed-form for the secrecy outage probability and the secrecy throughput with TAS-MRC and DSM-MRC schemes are derived to evaluate the secrecy performance, respectively. What's more, we explore the security diversity gain and coding gain based on the asymptotic secrecy outage probability. As the results, it demonstrates that DSM-MRC requires less CSI and is convenient for modulation and demodulation, but sacrifices some secrecy performance gains between two proposed schemes.
In this paper, we study the secure multi-antenna transmission with artificial noise (AN) under slow fading channels coexisting with randomly located eavesdroppers. We provide a comprehensive secrecy performance analysis and system design/optimization under a stochastic geometry framework. Specifically, we first evaluate the secrecy outage performance, and derive a closed-form expression for the optimal power allocation ratio of the information signal power to the total transmit power that minimizes the secrecy outage probability (SOP). Subject to a SOP constraint, we then propose a dynamic parameter transmission scheme (DPTS) and a static parameter transmission scheme (SPTS) to maximize secrecy throughput, and provide explicit solutions on the optimal transmission parameters, including the wiretap code rates, the on-off transmission threshold and the power allocation ratio. Our results give new insight into secure transmission designs. For example, secrecy rate is a concave function of the power allocation ratio in DPTS, and AN plays a significant role under SOP constraints and in dense eavesdropper scenarios. In SPTS, transmission probability is a concave function of the power allocation ratio, and secrecy throughput is a quasi-concave function of the secrecy rate. Numerical results are demonstrated to validate our theoretical analysis.