Cooperative Cognitive Radio Research Articles

BER Performance Analysis of Energy Harvesting Underlay Cooperative Cognitive Radio Network With Randomly Located Primary Users and Secondary Relays

In this work, we investigate the error probability of an energy harvesting co-operative cognitive radio network (CRN) in the presence of Poisson field of primary users (PU). We consider the scenario where, after harvesting energy from primary transmitters (PTs), a secondary transmitter (ST) would transmit its symbol towards secondary destination (SD) through a suitable secondary relay from a group of randomly scattered idle nodes within a circular region. Several relay selection criteria have been considered for relay node selection. Performance of a secondary transceiver has been analysed in terms of probability of error. Relationships among the bit error ratio (BER) performance of an ST and several other network entities such as density of PUs, transmit power of PTs and required transmit power of ST have also been investigated through detailed analysis. Numerical results are provided to assess the precision of derived analytical expressions.

A New Hardware-Efficient Spectrum-Sensor VLSI Architecture for Data-Fusion-Based Cooperative Cognitive-Radio Network

This article presents a hardware-friendly algorithm and architecture for cooperative spectrum sensing (CSS) in the data-fusion-based cognitive-radio (CR) network. The proposed VLSI-algorithm is based on the iterative power method and deflation technique that alleviate the computational complexity of conventional CSS algorithm with minimal performance degradation. In this work, a new hardware-efficient VLSI architecture of cooperative spectrum sensor (CSR) for the data-fusion center is presented, which supports up to six secondary users in the cooperative CR network. Its performance analysis under fading channel environment has been carried out where it delivers 0.8 detection probability ( $P_{d}$ ) at −8 dB of channel SNR with a false alarm rate of 0.1. It shows the minimum performance degradation of 0.057 dB at $P_{d} = 0.88$ compared to the conventional algorithm. The suggested CSR architecture has been application-specific integrated circuit (ASIC)-synthesized and postlayout simulated in UMC 90 nm-CMOS process. Thus, it occupies 2.4 mm2 of the core area, consumes 36 mW of total power, and delivers a low sensing time of $60.41~\mu \text{s}$ while operating at a maximum clock frequency of 87.7 MHz. Comparison with the reported works indicates that the proposed design requires 40.3% lesser area, and it is 41% hardware efficient than the conventional implementation. Eventually, this design has been field-programmable gate array (FPGA) prototyped, and its functionality is verified in the real-world test environment.

Spectral efficiency enhancement of green metric cognitive radio network using novel channel design and intellectual African buffalo optimization

In an advance world, the field of information technology is full of contemporary wireless approaches as because of this the spectral efficiency and spectral sensing technology brings a broad interest in the Cooperative Cognitive Radio Network (CCRN). Besides, the Green metric CCRN spectral sharing is one of the efficient modern approaches compared with other traditional wireless technologies. Nevertheless, the distribution of spectral between the cooperative cognitive customers has dramatic challenges due to the collaboration between the licensed and unlicensed customers. Therefore, the motivation of this research work is to show the better performance of green metric CCRN using novel techniques. Here, a novel Markov Gaussian Wideband Distribution (MGWD) and Dynamic First-Rate Relay Protocol is developed for communication. Moreover, a novel Intellectual African Buffalo Optimization (IABO) is proposed to estimate the finest spectral sensing and false alarm detection. The implementation of this work is done on the MATLAB platform. Sequentially, the performance of green metric CCRN is estimated in terms of the communication ratio, spectral efficiency, outage probability, and throughput. Moreover, the simulation outcomes show that the developed method in CCRN attain higher throughput and diminished power consumption in terms of both Primary User (PU) and Secondary User (SU) successful transmission of probability compared with the other conventional strategies.

Hybrid Detection for Cooperative Cognitive Radio Using AWT and HDWT

A lot of research shows that spectrum is not effectively used in wireless communications. There are several gaps in spectrum that are unused. Cognitive radio (CR) is a smart technique of addressing inefficient usage of spectrum resources. Spectrum sensing is a vital task in cognitive radio systems. The objective of the spectrum sensing process is to investigate the presence and absence of primary user signals in different spectrum holes. To increase the feasibility of the spectrum sensing process, it can be implemented in a cooperative mode. The cooperative spectrum sensing depends on a decision making task at a group of secondary users. One of the most popular spectrum sensing techniques is the energy detection. Unfortunately, this technique fails in low SNR scenarios to give high detection results. So, there is a need for cooperative spectrum sensing in addition to noise reduction techniques to enhance the performance of the CR system. This paper presents noise reduction techniques based on additive wavelet transform (AWT) with homomorphic decomposition and Haar discrete wavelet transform (HDWT) with homomorphic decomposition to reduce the noise prior to the decision making process. This scenario is investigated with several fusion rules that are used for the cooperative spectrum sensing with fixed-time sensing. Simulation results prove that with OR fusion rule, the proposed scenario increases the probability of detection in the range of SNR from − 20 to − 15 dB using the AWT with homomorphic decomposition. The achievable throughput increases using the HDWT with homomorphic decomposition. The AND fusion rule is not recommended with the HDWT, but the probability of detection is high with the AWT. The majority fusion rule achieves high throughput with the HDWT and a high probability of detection with the AWT.

Robust Secure Beamforming Design for Cooperative Cognitive Radio Nonorthogonal Multiple Access Networks

By the integration of cooperative cognitive radio (CR) and nonorthogonal multiple access (NOMA), cooperative CR NOMA networks can improve the spectrum efficiency of wireless networks significantly. Due to the openness and exposure of wireless signals, secure communication is an important issue for cooperative CR NOMA networks. In this paper, we investigate the physical layer security design for cooperative CR NOMA networks. Our objective is to achieve maximum secrecy rate of the secondary user by designing optimal beamformers and artificial noise covariance matrix at the multiantenna secondary transmitter under the quality-of-service at the primary user and the transmit power constraint at the secondary transmitter. We consider the practical case that the channel state information (CSI) of the eavesdropper is imperfect, and we model the imperfect CSI by the worst-case model. We show that the robust secrecy rate maximization problem can be transformed to a series of semidefinite programmings based on S-procedure and rank-one relaxation. We also propose an effective method to recover the optimal rank-one solution. Simulations are provided to show the effectiveness of our proposed robust secure algorithm with comparison to the nonrobust secure design and traditional orthogonal multiple access schemes.

Overview of Cognitive Radio Networks

Cognitive radio (CR) allows the best use of dynamic access to spectrum and wide spectrum diversity to mitigate spectrum depletion issues and fulfil huge wireless networking requirements. This paper also illustrates, discusses, and focuses on some essential applications, a proactive spectrum sharing strategy using full-duplex (FD) in the cooperative Cognitive Radio Networks (CRN).

Secrecy Performance for Underlay Cooperative Cognitive Radio Network with Energy Harvesting and Transmit Antenna Selection Using MIMO Over Nakagami-m Fading Channels.

Secrecy Performance for Underlay Cooperative Cognitive Radio Network with Energy Harvesting and Transmit Antenna Selection Using MIMO Over Nakagami-m Fading Channels.

Outage probability analysis for relay-based cognitive radio network

This paper is delineating with relay-based subjective radio system (CRN) with different optional source hubs and numerous auxiliary goal nodes. The quality of service is mainly ability can be enhanced with proper resource allocation. The link value is preserved by keeping SNR above a threshold called minimum protection ratio. Uplink resource allocation based on hybrid cooperative CR network (HCCRN) is considered in which licensed radio and cognitive radio are combined. Cognitive relay is utilised for range extension to attain greater capacity. CRN stands for cognitive radio network. Medium access layer network coding (MALNC) is connected with two sorts of full duplex transfer to be specific amplify and forward (AF), decode and forward (DF) for the fruitful transmission of data. Identification of data at the collector is anticipated by multiple range groups. Utilisation of MALNC lessens to the quantity of vacancies required for correspondence. Log typical conveyances are utilised for divert parameter investigation within the sight of shadowing of sign because of huge hindrances in versatile radio correspondence. Blackout likelihood is portrayed for blurring channel. A variety of the estimation of mean, fluctuation and transmission rate is done to accomplish an effective framework.

Outage probability analysis for relay-based cognitive radio network

This paper is delineating with relay-based subjective radio system (CRN) with different optional source hubs and numerous auxiliary goal nodes. The quality of service is mainly ability can be enhanced with proper resource allocation. The link value is preserved by keeping SNR above a threshold called minimum protection ratio. Uplink resource allocation based on hybrid cooperative CR network (HCCRN) is considered in which licensed radio and cognitive radio are combined. Cognitive relay is utilised for range extension to attain greater capacity. CRN stands for cognitive radio network. Medium access layer network coding (MALNC) is connected with two sorts of full duplex transfer to be specific amplify and forward (AF), decode and forward (DF) for the fruitful transmission of data. Identification of data at the collector is anticipated by multiple range groups. Utilisation of MALNC lessens to the quantity of vacancies required for correspondence. Log typical conveyances are utilised for divert parameter investigation within the sight of shadowing of sign because of huge hindrances in versatile radio correspondence. Blackout likelihood is portrayed for blurring channel. A variety of the estimation of mean, fluctuation and transmission rate is done to accomplish an effective framework.

Outage Analysis in Underlay OFDMA Based Cooperative Cognitive Radio Networks

Background: Efficient resource allocation in Cooperative Cognitive Radio Network (CCRN) is necessary in order to meet the challenges in future wireless networks. With proper resource allocation, the Quality of Service (QoS) comprising of outage probability and data rate are evaluated in this paper and sufficiently improved with proper subcarrier allocation. Objective: Another important parameter is Signal to Interference Ratio (SIR) which should be above a threshold called minimum protection ratio to maintain the required QoS. Results: The network considered is Orthogonal Frequency Division Multiple Access (OFDMA) based Hybrid Cooperative Cognitive Radio Network (HCCRN) in downlink in which licensed as well as unlicensed resources are used by cognitive user depending on it’s availability keeping the interference constraint in limit. The number of subcarriers required is different for every user depending upon its distance from the base station to satisfy the requirement of data rate which depends on the experienced SIR. To avoid outage of users at the boundary of a cell, it is necessary to allocate more number of subcarriers. Conclusion: It is observed that for a given user position and outage probability, as the number of subcarrier allocation in a subchannel increases high data rates can be achieved. This analysis can be useful in allocation of subcarriers to users depending upon their position.

Enhanced physical layer security for cognitive radio systems through joint spectrum access and power allocation

Physical layer (PHY) security is an important issue in wireless communication systems. In this study, the authors investigate the interactions between the PHY security performance and the spectrum access technique in a cooperative cognitive radio (CR) network. In the classical spectrum access, if the measured energy on a given subchannel is less than a threshold, the subband is dedicated for CR transmission. Here, they consider a probabilistic spectrum access (PSA), which assigns to each primary subchannel a probability which is determined according to the measured energy on that subchannel. In addition, both spectrum access and CR power allocation are performed simultaneously. They formulate the general outage probability and some important PHY security performance metrics, such as average secrecy rate, secrecy outage probability, and probability of positive secrecy rate in terms of the spectrum access and optimal power allocation functions. The authors' numerical analysis indicates that the PSA method achieves a superior PHY security and outage performance compared to the classical threshold-based spectrum sensing and power allocation method.

Outage Analysis of Relay-Assisted NOMA in Cooperative Cognitive Radio Networks with SWIPT

In this paper, we investigate a relay-assisted cooperative spectrum sharing for the considered non-orthogonal multiple access (NOMA) scheme in cognitive radio networks, where the relay node assists the base station (BS) to transmit the superimposed composite signal to two receivers by utilizing an amplified-and-forward (AF) technique with simultaneous wireless information and power transfer (SWIPT). The exact expressions for outage probabilities of two receivers are derived in closed forms. Moreover, a joint optimization of power allocation and the proportion of information splitting for energy harvesting is proposed in terms of energy efficiency (EE) maximization under required data reliability. Simulation results validate the analytical results since the analytical results match well with simulation results and demonstrate the performance advantages of the proposed scheme over other schemes and direct transmission.

From Cognitive to Intelligent Secondary Cooperative Networks for the Future Internet: Design, Advances, and Challenges

Cognitive Radio (CR) technology was first introduced to solve the problem of radio spectrum under-utilization. A cognitive radio network consists of smart radio devices that have the ability to sense radio environment variables and take actions accordingly. To realize their full potential and to become fully cognitive, the CR nodes need to be equipped with learning and reasoning capabilities. Machine learning has been one of the enabling vehicles for intelligent CR networks. Inspired by the cognition cycle of a CR node, over the past years there has been an ever growing interest in using machine learning techniques to enhance the performance of CR networks. In this article, an overview of the various learning techniques currently used in the literature of CR networks is given. We focus on feature classification and clustering algorithms, and their application in cooperative CR networks. We outline the steps to establishing a learning-based cooperative secondary network, highlighting factors that impact detection performance. Additionally, current state-of-the-art learning-based applications in Cognitive Internet of Things (CIoT) are presented. Finally, the key challenges and future directions of intelligent cognitive networks are discussed.

Secure cooperative spectrum sharing in full-duplex multi-antenna cognitive radio networks with jamming

We consider a secure overlay cognitive radio network with an eavesdropper wherein a multi-antenna secondary transmitter performs transmission in primary spectrum, on the condition that it helps primary system to perform secure and reliable transmission via cooperative relaying and jamming. To improve secrecy performance of primary network, we propose full-duplex jammer protocol and zero-forcing based beamforming design, which completely cancels the interferences at the primary and secondary users and simultaneously avoids the leakage of confidential information to eavesdropper. Moreover, we present new expressions for the average secrecy rate and a lower bound for the secrecy outage probability. Furthermore, an asymptotic analysis in the high signal-to-noise ratio regime is carried out to obtain closed-form average secrecy rate. Our analytical findings reveal that by exploiting beamforming and full-duplex at the secondary transmitter secrecy outage probability can be significantly reduced and a diversity order of min (NR-1,NT-2) can be achieved where NR and NT are the number of received and transmit antennas at secondary transmitter. Simulation results also demonstrate that as compared to the half-duplex scenario without jamming, the proposed cooperative FD overlay CR scheme with jamming can improve the average secrecy rate up to 224%.

Enhancing the Spectrum Sensing Performance of Cluster-Based Cooperative Cognitive Radio Networks via Sequential Multiple Reporting Channels

In cluster-based cooperative cognitive radio networks (CCRNs), spectrum sensing and decision making processes to determine whether the primary user (PU) signal is present or absent in the network are very important and vital issues to the utilisation of the idle spectrum. The reporting time delay is a very important matter to make quick and effective global decisions for the fusion center (FC) in a cluster-based CCRNs. In this paper, we propose the concept of multiple reporting channels (MRC) for cluster-based CCRNs to better utilize the reporting time slot by extending the sensing time of secondary users (SUs). A multiple reporting channels concept is proposed based on frequency division multiple access to enhance the spectrum sensing performance and reduce the reporting time delay of all cluster heads (CHs). In this approach, we assign an individual reporting channel to each cluster for reporting purposes. All the SUs in each cluster sequentially pass their sensing results to the corresponding cluster head (CH) via the assigned single reporting channel, which extends the sensing time duration of SUs. Each CH uses the dedicated reporting channel to forward the cluster decision to the FC that makes a final decision by using the “K-out-of-N” rule to identify the presence of the PU signal. This approach significantly enhances the sensing time for all SUs than the non-sequential as well as minimize the reporting time delay of all CHs than sequential single channel reporting approach. These two features of our proposed approach increase the decision accuracy of the FC more than the conventional approach. Simulation results prove that our proposed approach significantly enhances the sensing accuracy and mitigate the reporting time delay of CH compared to the conventional approach.

Outage Performance of Power Beacon-Aided Multi-Hop Cooperative Cognitive Radio Protocol Under Constraint of Interference and Hardware Noises

In this paper, we evaluate end-to-end outage probability of a multi-hop decode-and-forward relaying protocol in underlay cognitive radio network. In the proposed protocol, named COOP, secondary nodes including source and relays have to harvest radio-frequency energy from multiple secondary power beacons, and adjust their transmit power, follows a pre-determined interference threshold given by multiple primary users. To enhance the outage performance for the secondary network under an joint constraint of the interference threshold, Rayleigh fading channel and hardware noises caused by imperfect transceiver hardware, the secondary relays on the source-destination path cooperate to forward the source data to the destination. Particularly, they attempt to receive the source data from their previous nodes, and forward it to the secondary destination if requested. Moreover, whenever the destination cannot receive the source data successfully, a successful relay that has the shortest distance to the destination is selected for retransmission. Due to usage of the cooperative transmission, the proposed COOP protocol obtains better performance, as compared with the corresponding multi-hop relaying one (denoted DIRECT) which only uses direct transmission at each hop. We evaluate the outage performance of COOP and DIRECT via both simulation and theory. The obtained results present a significant performance enhancement, as comparing COOP with DIRECT.

Throughput Maximization by Optimizing Secondary Users in a Cooperative Cognitive Radio Network using Hard Fusion Rules

Cognitive radio network is a promising technology for enabling secondary users to utilize the licensed spectrum of the primary user without causing interference. The data trans- mitted by the secondary users through primary channel without affecting the primary user is known as channel throughput. In cooperative spectrum sensing(CSS) as the number of secondary users increases the channel throughput increases which in turn reduces the spectrum efficiency due to more spectrum wastage. Therefore in this paper, channel throughput is maximized by optimizing secondary users proposed and throughput for variable secondary users for OR and AND fusion rules is investigated. The optimal secondary users is estimated mathematically and simulation results shows the variation of throughput for variable number of secondary users.

Energy-Aware Relay Selection Improves Security-Reliability Tradeoff in Energy Harvesting Cooperative Cognitive Radio Systems

This article investigates the physical layer security for a cooperative cognitive radio (CCR) system with energy-harvesting (EH) technique, which consists of a cognitive source (CS), multiple cognitive relays (CRs) and a cognitive destination (CD) as well as multiple eavesdroppers (Es) who are considered to tap the confidential transmission from CS via CRs to CD. Both CS and CRs are equipped with energy-harvesters to harvest energy from the surrounding radio frequency environment. Additionally, in order to guarantee the quality-of-service of primary communications, the transmit powers of CS and CRs are limited by the maximum tolerant power at primary destination. Depending on the availability of channel state information (CSI) of wireless energy links from primary transmitter (PT) to CRs, we respectively propose non-energy aware relay selection (NEARS) and energy aware relay selection (EARS) schemes for protecting the transmission from CS via CRs to CD from leaking to Es. We consider the use of the security-reliability tradeoff (SRT) to measure the performance of NEARS and EARS schemes. For the purpose of comparison, we also carry out the analysis of SRT performance for conventional direct communication (DC). Furthermore, the closed-form expressions of outage probability and intercept probability for NEARS and EARS schemes are derived and numerical results show that the SRT performance of EARS is better than that of DC and NEARS schemes.

Quantized Soft-Decision-Based Compressive Reporting Design for Underlay/Overlay Cooperative Cognitive Radio Networks

Cooperative spectrum sensing (CSS) systems use underlay or overlay strategies to identify underused or unused bands to achieve higher spectrum utilization. In hybrid underlay and overlay systems, spectrum sensing results may be sparse and a general reporting strategy is required to take multiple spectrum usage status into account. In this paper, we propose a general quantized soft decision (QSD) based compressive sensing and reporting strategy for hybrid systems. Our objective is to provide a general framework to report more reliable sensing results to improve the sensing precision and reduce the collision probability with the low complexity. To this end, the soft sensing decisions are quantized to multiple levels, then they are compressed and encoded, while the characteristic information of secondary users (SUs) including the index of the SUs, the interference tolerance level etc, is transmitted over equivalent bit channels. Furthermore, considering that different users may have different quality of service requirements, we propose four methods to allow SUs to deliver local sensing results with different precisions. Simulations are performed over additive white Gaussian noise (AWGN) and Rayleigh fading channels. The results validate the theoretical analysis, and demonstrate that our scheme effectively improves the sensing decision precision and reduces the collision probability.

Feedback Bits Allocation for Guaranteed Bit Rate Services in Cooperative Cognitive Radio Networks.

As the number of users using multimedia sharing services increases, the need to ensure the minimum data rate of wireless users increases. Meanwhile, in the cooperative cognitive radio (CR) network, it is important to provide the quality-of-services for secondary users (SUs) while satisfying the inter-network interference constraint from secondary transmitters to primary users (PUs). Under the limited feedback resource constraint, this paper proposes a feedback bits allocation scheme for the guaranteed bit rate services of SUs while satisfying the inter-network interference constraint. This paper investigates how many feedback bits between the ST and PUs are required to guarantee the minimum data rate of SUs and then proposes a feedback bits allocation scheme that maximizes the average sum rate of SUs while reducing the outage probability of SUs.