Secondary Destination Node Research Articles

Full‐duplex jamming for physical layer security improvement in NOMA‐enabled overlay cognitive radio networks

AbstractIn this paper, we analyze the physical layer security (PLS) performance of nonorthogonal multiple access (NOMA)‐enabled overlay cognitive radio networks (NOMA‐OCRNs) in the presence of an external passive eavesdropper. Here PLS is expressed in terms of the secrecy outage probabilities (SOPs) experienced by the primary user (PU) and secondary user (SU). We obtain approximate expressions for the SOPs of both PU as well as SU assuming a jamming‐free environment, where both primary and secondary destination nodes are half‐duplex devices. To improve the SOP performance, we propose a jamming‐assisted framework, where full‐duplex destination nodes are employed, which are capable of transmitting jamming signals to confound the eavesdropper. Approximate expressions for the SOPs of PU and SU are derived for the jamming‐assisted framework as well. It is demonstrated that the proposed jamming‐assisted framework significantly reduces the SOPs compared to the jamming‐free scenario. We also determine optimal power allocation coefficients (OPACs) for PU and SU at the secondary transmitter that maximizes the total secrecy throughput of the jamming‐assisted NOMA‐OCRN with FD destinations. It is shown that the suggested OPAC significantly enhances the total secrecy throughput, compared to the default selection of the PAC.

Optimization on information freshness for multi‐access users with energy harvesting cognitive radio networks

AbstractFor the multi‐access channel wireless sensor network scenario with limited channel resources, the transmission of real‐time information needs to consider the channel environment, spectrum utilization and the freshness of information. First, we present a cognitive network model where secondary user (SU) shares the primary user (PU) spectrum through the underlay scheme. The sensor nodes with energy harvesting (EH) capabilities dynamically monitor changes in the surrounding environment and transmit status updates to the common secondary destination node. Considering the stability of the data queue in the SU as well as the working state and stable service interference constraints of PU, an optimization problem of minimizing the average AoI and average peak AoI (PAoI) of the EH node is proposed. Second, two policies are used to solve the above problems, including the decentralized probabilistic‐random‐access (PRA) policy and the drift plus penalty (DPP) policyin. In PRA policy, two SU nodes make independent transmission decisions based on corresponding probability distributions, and in DPP policy, the Lyapunov optimization framework is used to optimize scheduling decisions in the timeslots for optimizing the age of data packets. The simulation results show that the optimization of AoI under the DPP policy is more significant than the PRA policy, which can effectively improve the timeliness and freshness of data packets.

Outage performance of underlay cognitive radio networks over mix fading environment

In this paper, the underlay cognitive radio network over mix fading environment is presented and investigated. A cooperative cognitive system with a secondary source node S, a secondary destination node D, secondary relay node Relay, and a primary node P are considered. In this model system, we consider the mix fading environment in two scenarios as Rayleigh/Nakagami-m and Nakagami-m/Rayleigh Fading channels. For system performance analysis, the closed-form expression of the system outage probability (OP) and the integral-formed expression of the ergodic capacity (EC) are derived in connection with the system's primary parameters. Finally, we proposed the Monte Carlo simulation for convincing the correctness of the system performance.

Dual Antenna Selection in Secure Cognitive Radio Networks

This paper investigates data transmission and physical-layer secrecy in cognitive radio (CR) networks. We propose to apply full-duplex transmission and dual antenna selection at a secondary destination node. With the full-duplex transmission, the secondary destination node can simultaneously apply the receiving and jamming antenna selection to improve the secondary data transmission and primary secrecy performance, respectively. This describes an attractive scheme in practice: Unlike that in most existing approaches, the secrecy performance improvement in the CR network is no longer at the price of the data transmission loss. The outage probabilities for both the data transmission and physical-layer secrecy are analyzed. Numerical simulations are also included to verify the performance of the proposed scheme.

On Multicast Capacity and Delay in Cognitive Radio Mobile Ad Hoc Networks

In this paper, we focus on the capacity and delay tradeoff for multicast traffic pattern in cognitive radio mobile ad hoc networks (MANETs). In our system model, the primary network consisting of n primary nodes overlaps with the secondary network consisting of m secondary nodes in a unit square. Assume that all nodes move according to an independent and identically distributed mobility model, and each primary node serves as a source that multicasts its packets to kp primary destination nodes, whereas each secondary source node multicasts its packets to ks secondary destination nodes. Under the cell partitioned network model, we study the capacity and delay for the primary networks under two communication schemes, i.e., noncooperative scheme and cooperative scheme. The communication pattern considered for the secondary network is cooperative scheme. Given that m = n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">β</sup> (β > 1), we show that per-node capacities O(1/k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> ) and O(1/k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> ) are achievable for the primary network and the secondary network, with average delays Θ(n log k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> ) and Θ(m log k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> ), respectively. Moreover, to reduce the average delay in the secondary network, we employ a redundancy scheme and prove that a per-node capacity O(1/k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> √m log k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> ) is achievable with average delay Θ(√m log k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> ). We find that the fundamental delay-capacity tradeoff in the secondary network is delay/capacity ≥ O(mk <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> log k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> ) under both cooperative and redundancy schemes.

Full Duplex Relay Based Cognitive Radio System with Physical Layer Network Coding

In this paper, a full duplex relay (FDR) based cognitive radio (CR) system is proposed with two secondary source nodes and two secondary destination nodes. The concept of physical layer network coding (PLNC) is applied on decode and forward (DF) FDR to ensure that both source nodes can transmit data to both destination nodes. Further, the availability of multiple spectrum bands enables CR system to decode source symbols at destination nodes. The major advantage of the proposed system with FDR and PLNC is that it requires only one time slot to send the data from both the source nodes to both the destination nodes. If FDR is replaced with half duplex relay (HDR), 2 time slots are required for the CR system. If PLNC is not applied at the DF relay, the CR system would require 2 or 4 time slots when FDR or HDR is employed, respectively. In Nakagami-$$m$$m fading channels environment, analytical expressions are derived for end-to-end outage performance of the proposed PLNC based system in the presence of echo interference at the FDR and with HDR in the place of FDR. The outage performance of the proposed CR system is analyzed for various scaling and shape parameters of Nakagami-$$m$$m fading channels.

Distributed space‐time–frequency block code for cognitive wireless relay networks

In this study, the authors consider cooperative transmission in cognitive wireless relay networks (CWRNs) over frequency-selective fading channels. They propose a new distributed space-time–frequency block code (DSTFBC) for a two-hop non-regenerative CWRN, where a primary source node and multiple secondary source nodes convey information data to their desired primary destination node and multiple secondary destination nodes via multiple cognitive relay nodes with dynamic spectrum access. The proposed DSTFBC is designed to achieve spatial diversity gain as well as allow for low-complexity decoupling detection at the receiver. Pairwise error probability is then analysed to study the achievable diversity gain of the proposed DSTFBC for different channel models including Rician fading and mixed Rayleigh–Rician fading.

Performance of Cooperative Spectrum-Sharing Systems with Amplify-and-Forward Relaying

This paper investigates the performance of using cooperative relaying technique in spectrum-sharing cognitive radio (CR) systems while considering constraints on the average received-interference at the primary receivers. Specifically, we consider that the communication between a secondary source and its destination nodes is assisted by an intermediate relay that uses amplify-and-forward (AF) strategy. In this context, we obtain closed-form expressions for the probability density function (PDF) of the received signal-to-noise ratio (SNR) at the secondary destination node for different channel fading distributions, namely, Nakagami and Rayleigh. Then, the end-to-end performance of the proposed cooperative relaying spectrum-sharing system is investigated in terms of the overall achievable capacity and outage probability of the secondary user communication. Finally, simulation results sustaining our theoretical analysis are provided and comparisons illustrating the overall performance of the cooperative spectrum-sharing system are drawn for different propagation conditions.