Cognitive Radio Network System Research Articles

Performance evaluation for secondary users in finite-source cognitive radio networks with dynamic preemption limit

Primary users (PUs) have higher priority and are able to preempt the channels used by secondary users (SUs) in cognitive radio networks (CRNs). The traditional complete preemption mechanism does not restrict the preemption behavior of PUs, and it isn’t easy to guarantee SUs’ transmission performance when PU packets arrive frequently. To ensure SUs’ most essential continuous transmission, we propose a preemption mechanism with a dynamic preemption limit in a finite-source CRN system. The preemption limit is adjusted dynamically by the central controller in accordance with transmitted SU packets’ quantity to restrict PUs’ preemption behavior. We develop a 2-dimensional Markov-chain based on this to construct a discrete-time preemptive queueing model. With the solved system’s steady-state probability distribution, we obtain some performance index expressions. Moreover, we analyze the system’s performance in various network conditions and compare our proposed preemption mechanism to the traditional complete preemption mechanism to demonstrate its superiority by employing numerical experiments. Numerical results show that the proposed preemption mechanism with a dynamic preemption limit can improve SUs’ transmission performance and adapt to the more complex network environments. Finally, we create a utility function to calculate the ideal amount of SUs that will provide the optimal comprehensive performance.

A Survey of Game Theoretical Approach in Cognitive Radio Network and 5G-6G Communications

The development of telecommunications, especially wireless communication, requires data transmission at high speed and wide bandwidth to support 5G-6G communication services. For this reason, it is necessary to have a network with adaptive capabilities in managing and improving performance parameters independently through an intelligent radio network system or better known as Cognitive Radio Network (CRN). The use of CRN in several implementations such as Cognitive Radio Ad Hoc Network (CRAHN), Cognitive Radio Vehicular Ad Hoc Networks (CR-VANET), Intelligent CRN and even 6G-CRN has also been widely used. Another method that is also used to optimize system performance independently is through the Game Theory (GT) approach. Game theory can be implemented on CRN as well as on 5G-6G communications. The use of GT in the CRN system provides improvements in terms of increasing system performance such as reducing interference and bit error rate (BER), increasing throughput and Signal to Interference plus Noise Ratio (SINR), power efficiency, increasing utility and resource capacity and being able to achieve convergence or reach the Nash equilibrium state more rapidly. Meanwhile, the use of GT in 5G-6G communication and other technologies are related to the power control, resource allocation, spectrum sharing, channel estimation, channel selection and Quality of Service (QoS) or Quality of Experience (QoE). In general, the use of GT can help to improve the overall performance of a system.

Internet of Things (IoT) for MC-CDMA-Based Cognitive Radio Network (CRN) in 5G: Performance Results

Both the internet-connected devices, i.e. IoT and Cognitive Radio Network (CRN) are considered to be the future technologies for the fifth generation of cellular wireless standards (5G). On the one hand, Internet of Things (IoT) focuses primarily on how to allow general objects to see, hear, and smell their own physical environment and make them connected to share the observations. On the other hand, a CRN is based on a complex spectrum allocation system, and licenced primary users (PUs) or unlicenced secondary users (SUs) are allowed to share the spectrum, provided they do not cause significant interference. The IoTs are meaningless if IoT objects are not equipped with cognitive radio capability. In cognitive radio, it is important to control the transmission power of SUs so that the interference should not be harmful to the quality of service of PUs. In this paper, the authors addressed the effects of imperfect power control between primary users (PUs) and the secondary users (SUs) of an IoT-based CRN. The effect of the co-channel interference (CCI) and adjacent channel interferences (ACIs) occurring in CRN using MC-CDMA system is also analysed. A new expression of the signal-to-interference-noise ratio (SINR) for CRN-based MC-CDMA system over a Nakagami-[Formula: see text] fading channel with imperfect power control condition is derived and investigated. The performance of IoT-based CRN using MC-CDMA system over the frequency selective multipath fading channel is examined with varying the number of users, the SINR per bit, number of fading path and number of sub-carriers. From the simulation results, we have seen that the SINR performance is affected by these parameters. The result of the analysis will provide relevant information to design the physical layer protocol for high-speed IoT-based CRN system for 5G.

System Imperfections on the Overall Performance of MC-CDMA-Based Cognitive Radio Network (CRN) System

Cognitive radio network (CRN) is considered to be the future technology for the fifth generation of cellular wireless standards (5G). CRN is based on a complex spectrum allocation system, and licensed primary users (PUs) or unlicensed secondary users (SUs) are allowed to share the spectrum, provided that they do not cause significant interference. In cognitive radio, it is important to control the transmission power of SUs so that the interference should not be harmful to the quality of service of PUs. In this paper, the authors addressed the impact of system imperfections on the overall performance of multi-carrier code division multiple access (MC-CDMA)-based CRN system. A new expression of the signal-to-interference-noise ratio (SINR) for MC-CDMA-based CRN system over a Rayleigh fading channel without any power control condition among the PUs and SUs is derived and investigated. The performance of MC-CDMA-based CRN system over the frequency selective multi-path fading channel is examined by varying the number of users, the signal-to-noise-ratio (SNR) per bit, number of fading path and number of subcarriers, respectively. From the simulation results, we have seen that the SINR performance is affected by these parameters. The analysis presented in this paper shows the impact of lack of a controlling mechanism on transmitted signal power affecting the between PUs and SUs ultimately system performance. The result of the analysis will provide relevant information to design the physical layer protocol for high speed CRN system for 5G.

Threshold selection and cooperation in fading environment of cognitive radio network: Consequences on spectrum sensing and throughput

In this paper, we have analyzed the effects of cooperative spectrum sensing and threshold selection over the performance of cognitive radio network (CRN) using energy detector in the fading environment. Firstly, we have compared the receiver operating characteristics (ROC) curve of both the cooperative and non-cooperative scenario for different fading environments. Further, we have illustrated the probability density function (PDF) of binary hypothesis for proposed CRN system, and analyzed the necessity of dynamic selection of threshold over that of the fixed threshold selection. In addition to this, we have compared the spectrum sensing performance and throughput of proposed CRN for fixed and dynamic threshold selection approaches on the spectrum sensing error at low and high signal-to-noise (SNR) ratio. Moreover, we have improved the sensing performance of proposed CRN by employing cooperative spectrum sensing with dynamic threshold selection scheme. Further, the percentage improvement in detection probability, throughput and total error probability of the proposed system model has been presented.

Secrecy outage probability of inter‐vehicular cognitive radio networks

SummaryHerein, we consider an underlay cognitive radio network (CRN) where mobile secondary user wishes to transmit a confidential information to the secondary destination in the presence of an illegitimate eavesdropper which is trying to steal the classified message signal. The proposed scenario can be viable for a secondary safety task force working with a primary regiment, which wishes to transmit the confidential information to the commander while an eavesdropper is trying to intercept the classified information. In the analysis, two novel power allocation methods are considered by assuming perfect and limited feedback channels of the primary network, and for both methods, exact and asymptotic expressions of secrecy outage probability (SOP) are derived for N*Nakagami‐m fading channels which are used to model fading channels such as mobile‐to‐mobile/vehicle‐to‐vehicle communication systems where the nodes are moving into a rich scattering environment. We further verified our analytic results through Monte‐Carlo simulations. It is shown from the numerical results that the cascading degree of the channels has a worsening effect on the secrecy outage performance of the CRN systems.

AADS: DEVELOPING AGENT ASSISTED DEFENSE SYSTEM AGAINST HARMFUL ATTACKS IN COGNITIVE RADIO NETWORK

Cognitive radio network (CRN) is an emerging technology that provides ability of adapting operating parameters to wireless devices in order to overcome spectrum scarcity problems. The paper mainly focused on three major attacks held on CRN such as, primary user emulation (PUE), spectrum sensing data falsification (SSDF), and eavesdropper attacker. To overcome attacks, this paper designs an effective agent assisted defence system in CRN. Initially network is partitioned into four different groups based on communication range of PBS. To mitigate SSDF attack the malicious node is isolated from the network. This decision is made by tri-state Markov chain model (MCM) which predicts future activity of the node. Communication in the network is protected by hybrid advance encryption with Diffie-Hellman encryption (HAES-DHE) algorithm to alleviate eavesdropper attack. Experimental result shows promising improvements in probability of detection, probability of miss detection, estimation of attack strength, average estimate of honest nodes and throughput.

Standard Condition Number Distributions of Finite Wishart Matrices for Cognitive Radio Networks

The standard condition number (SCN) in random matrix theory (RMT) has widely been employed in cognitive radio networks (CRNs). The paper studies the SCN distributions of central and complex Wishart matrices with finite dimensions. The exact and closed-form expressions of SCN distributions are first proposed in sum of multiple polynomials. The proposed formulations provide an efficient way to determine probability density function and cumulative distribution function of the SCN in finite RMT. In particular, the specific SCN distributions of triple Wishart matrix are initially presented. The theoretical and precise sensing thresholds for cooperative spectrum sensing (CSS) systems in CRNs are calculated using the proposed SCN distributions. Numerical results indicate that the proposed theoretical SCN distributions match the empirical SCN distributions very well. Furthermore, the exact SCN-based CSS systems are able to obtain higher sensing performance than the asymptotic SCN-based schemes because precise sensing thresholds can be determined.

Proposed Scheme for Maximization of Minimal Throughput in MIMO Underlay Cognitive Radio Networks

In cognitive radio networks (CRNs), the most critical issue is to increase the secondary throughput while assuring the quality of service of primary users (PUs). In this paper, a proposed optimal power allocation scheme using genetic algorithm is suggested for a multiple-input-multiple-output (MIMO) system in CRN. This scheme is used to maximize the secondary throughput under interference constraints in a system model of multiple secondary user (SU) pairs coexisting with multiple PU pairs in an underlay spectrum sharing network. For the sake of comparison, the minimal throughput among all SUs is compared with other power allocation schemes, namely, maximum–minimum-throughput-based power assignment (MMTPA) and equal power assignment (EPA). Simulation results show that, our proposed scheme gives the maximum–minimum secondary throughput among all other stated schemes. Moreover, unlike MMTPA, our proposed approach maximizes the throughput of all SUs not only the minimal throughput among all SUs.

Adaptive cognitive radio energy-harvesting scheme using sequential game approach

Radio frequency (RF) energy transfer and harvesting techniques have recently become alternative methods to overcome the barriers that prevent the real-world wireless device deployment. For the next-generation wireless networks, they can be key techniques. In this study, we develop a novel energy-harvesting scheme for the cognitive radio (CR) network system. Using the sequential game model, data transmission and energy harvesting in each device are dynamically scheduled. Our approach can capture the wireless channel state while considering multiple device interactions. In a distributed manner, individual devices adaptively adjust their decisions based on the current system information while maximizing their payoffs. When the channel selection collision occurs, our sequential bargaining process coordinates this problem to optimize a social fairness. Finally, we have conducted extensive simulations. The results demonstrate that the proposed scheme achieves an excellent performance for the energy efficiency and spectrum utilization. The main contribution of our work lies in the fact that we shed some new light on the trade-off between individual wireless devices and CR network system.

A Cyclostationarity-Based Implicit Channel for Cognitive Radio Applications

Cognitive Radio (CR) technology is believed to be a favorable complement to current and future wireless communication systems, due to its distinctive capability in promoting spectrum efficiency. However, as the number of CR applications increases, coexistence has become a vital issue for radio systems in CR networks. In this paper, a Cyclostationarity-based Implicit Channel (CIC) is proposed to assist conflict-avoidance coexistence for radio systems in the CR networks with Orthogonal Frequency Division Multiplexing (OFDM). First, an asymptotic maximum likelihood demodulation scheme is derived analytically based on a bijective-mapping based modulation. Subsequently, the performance of the proposed CIC is investigated via numerical simulations. It is demonstrated that the CIC can work effectively as an information sharing platform. Moreover, the CIC can work as an independent add-on module to the data bearing OFDM schemes, with minimum impact on the existing systems. Therefore, it is a highly attractive solution for delivering coexistence information in CR networks.

Intrusion detection system (IDS) for combating attacks against cognitive radio networks

While cognitive radio networks (CRNs) present a promising solution to solve the scarcity of the radio spectrum, they are still susceptible to security threats. Until now, only a few researchers considered the use of intrusion detection systems (IDSs) to combat these threats against CRNs. In this article we describe a CRN based on IEEE wireless regional area network (WRAN) and describe some of the security threats against it. For the secondary users in the CRN to quickly detect whether they are being attacked, a simple yet effective IDS is then presented. Our proposal uses non-parametric cumulative sum (cusum) as the change point detection algorithm to discover the abnormal behavior due to attacks. Our proposed IDS adopts an anomaly detection approach and it profiles the CRN system parameters through a learning phase. So, our proposal is also able to detect new types of attacks. As an example, we present the case of detection of a jamming attack, which was not known to the IDS beforehand. The proposed IDS is evaluated through computer based simulations, and the simulation results clearly indicate the effectiveness of our proposal.

Optimization of spectrum utilization in cognitive radio system

In Cognitive Radio (CR) networks, CR user has to detect the spectrum channel periodically to make sure that the channel is idle during data transmission frame in order to avoid the collisions to the primary users. Hence recent research has been focused on the interference avoidance problem. Quality of Service (QoS) requirement of CR user will affect the time of data transmission in each frame. In this paper, in order to solve the interference avoidance and spectrum utilization problems without cooperation among CR users, a new scheme to obtain the optimal duration of data transmission frame is proposed to maximize the spectrum utilization and guarantee the protection to the primary users. The main advantages of our proposed scheme include the followings: (1) QoS requirement of CR user is concerned; (2) p-persistent Media Access Control (MAC) random access is used to avoid the collisions among CR users; (3) CR network system capacity is considered. We develop a Markov chain of the primary spectrum channel states and an exponential distribution of the CR user’s traffic model to analyze the performance of our proposed scheme. Computer simulation shows that there is an optimal data transmission time to maximize the spectrum utilization. However, the regulatory constraint of the collision rate to the primary users has to be satisfied at the expense of spectrum utilization. And also the tradeoff between the spectrum utilization and the capacity of the CR system is taken into account.