Cognitive Radio Wireless Networks Research Articles

An Improved Two-Hop Rendezvous Model With Buffer-Aided Relays in Channel-Hopping Cognitive-Radio Wireless Networks for Internet of Things

In this paper, two-hop transmissions in channel-hopping (CH) cognitive-radio wireless networks (CRWNs) with buffer-aided relays are studied. The two-hop relay (rendezvous) model is improved using symmetric CH sequences, which are more suitable for practical CRWNs than the old model using asymmetric ones. A proper buffer storage size in the relays is formulated to minimize the two-hop data-transfer latency. The lower and upper bounds of the steady-state maximum-time-to-rendezvous (MTTR) and throughput with relays are derived with formal proofs. Using the proper buffer size, both metrics can be better controlled and found no worse than twice the original MTTR and throughput without relays. To explore the impacts of utilization probability of Internet-of-Things (IoT) devices to their performances in a small-scale CRWN, the single-region rendezvous-success (RS) rate and throughput are formulated. For a large-scale CRWN, the model is extended to formulate the multi-region RS rate and throughput with and without relays for the first time. Numerical studies of these analytical models are performed and validated with computer simulations. In summary, the transmission range and number of rendezvousing IoT devices are improved in the large-scale CRWN with relays, and the multi-region RS rate and throughput with relays are found better than those without relays.

Construction of Asynchronous Relaxed Difference Set of Q-Ary Maximum-Length Channel-Hopping Sequences for Cognitive Radio Wireless Networks

Construction of Asynchronous Relaxed Difference Set of <i>Q</i>-Ary Maximum-Length Channel-Hopping Sequences for Cognitive Radio Wireless Networks

To mitigate primary user emulation attack trajectory using cognitive single carrier frequency division multiple access approaches: Towards next generation green IoT

AbstractThe growing cognizance of spectrum scarcity has become a more significant concern in wireless radio communications. Due to the exponential growth of data transmission in intelligent wireless sensor networks, energy spectrum detection has become a promising solution for resolving spectrum shortages. Primary user emulation attack (PUEA) has been identified as a significant attack vector in the cognitive radio (CR) domain's physical layer. In comparison, the CR is a promising method to increase spectrum efficiency by allowing unlicensed secondary users (SUs) to access licensed frequency bands without interfering with approved primary users (PUs). The study's primary findings are the methodology for preventing PUEA using authentication tags, which are unique sequences. This research blends SC‐FDMA with CR to protect CR networks from PUEA attacks, a Latin square (LS) matrix tag generation system is proposed to mitigate the PUEA effect. The technology is meant to provide effective authentication and protection against malicious users. In a secured environment, the LS tag technique is utilized to track and estimate the PU. For example, the BER of both techniques is virtually identical between 0 and 4 dB, while the BER performance of the suggested LS tag generation improves with increasing signal‐to‐noise ratio (SNR). As a result, the suggested LS tag generation is less susceptible to PUEA. To diminish the influence of PUEA in CR networks, an efficient enlightening approach for making the future Green Cognitive Radio Wireless networks structure is proposed. The simulation results also demonstrate the resilience of the proposed CR spectrum sensing techniques for energy‐efficient knowledge at varying degrees to reduce the adverse effects of environmental technologies.

Energy-efficiency performance of wireless cognitive radio sensor network with hard-decision fusion over generalized $$\alpha -\mu$$ fading channels

Energy-efficiency performance of wireless cognitive radio sensor network with hard-decision fusion over generalized $$\alpha -\mu$$ fading channels

Spectrum sensing performance of wireless cognitive radio sensor network with hard‐decision fusion over generalizedα−μfading channels

SummaryThe analysis of spectrum sensing performance of energy detection (ED)‐based wireless cognitive radio sensor network (ED‐WCRSN) with hard‐decision combining (HDC) is presented in this paper. Particularly, several network parameters are derived to estimate the performance of ED‐WCRSN, considering channel errors, noise, and generalized fading. In the considered network, first, cognitive radio sensor (CRS) senses a primary user (PU), gets sensing data, and then uses an ED to make a local binary decisions about PU's active or inactive status. In both sensing and reporting channels, the channel error probability is also taken into account. Next, HDC technique is used at control center (CC) to combine the locally obtained decisions, and a final decision about the status of the PU is made. To do so, first, the expression for the novel and analytical, which incorporates noise and fading, detection probability in a CRS is derived and validated using Monte Carlo simulations in MATLAB and using an experimental setup. Then, utilizing derived mathematical expressions, closed‐form expressions of an average error rate (AER), optimal numbers of CRSs, and detection thresholds under noisy and fading conditions are developed. The substantial influence of channel and network factors is assessed using receiver operating characteristics (ROC), complementary ROC, and AER. Finally, the impacts of channel and network parameters on ED‐WCRSN performance are explored. For numerous parameters of the considered network, the optimal values detection threshold and number of CRSs are also found.

Measurement of the Performance of a Cognitive Radio Spectrum Handoff Model

Wireless access has become an essential part of modern society. Consequently, new wireless applications and services, as well as the number of wireless users, are sharply increasing. Cognitive radio has improved the spectral efficiency of licensed radio frequency bands by accessing unused part of the band opportunistically without interfering with a licensed primary user. Spectrum mobility improves fast and smooth transition that lead to minimum performance degradation. An important requirement of mobility management protocols is a good performance in relation to spectrum handoff. To reduce the adverse effects of spectrum handoff interrupted secondary users may be provided with a higher priority over new secondary users for utilizing the available spectrum band. In this paper a queuing model of a spectrum handoff scheme for cognitive radio wireless networks is proposed. The handoff performance of the secondary users operating in a heterogeneous spectrum situation composed of licensed channels and unlicensed channels is tested., Three types of users: primary users, new secondary users, and handoff (Interrupted) secondary users are considered. The discrete event Simulator Matrix Laboratory (MATLAB) package tool is used to carry numerical calculations illustrating the effect of a priority queuing system on the performance of handoff of Secondary Users (SUs).

New Asynchronous Channel-Hopping Sequences for Cognitive-Radio Wireless Networks

In this paper, one family of identification-(ID)-based and one family of non-ID-based asynchronous channel-hopping (CH) sequences are constructed for supporting cognitive-radio wireless networks (CRWNs) in a homogeneous channel setting. The novelty lies in the use of two-dimensional (2-D) algebraic algorithms to properly arrange the linear- and quadratic-congruence sequences in the prime field; channel rendezvous are guaranteed to occur among all the elements (i.e., licensed channels) in at least one of the columns between any two CH matrices. As a result, the new asynchronous CH sequences always have uniform time-to-rendezvous (TTR) structures and satisfy the desirable design criteria of short periods, full degree-of-rendezvous (DoR), and even channel use (ECU). The studies show that the new constructions have the best balance between the full DoR, ECU, short period, small TTR mean and variance, and shortest maximum-time-to-rendezvous (MTTR) and maximum-first-time-to-rendezvous (MFTTR) in their respective categories of constructions. A short period can save memory in small sensors and mobile devices and are suitable for the Internet-of-Things and device-to-device communications. A short MTTR/MFTTR and a small TTR mean/variance can improve the rendezvous frequency and shorten the latency, thus enhancing and stabilizing the throughput.

Optimal precoders and power splitting factors in multiuser multiple‐input multiple‐output cognitive decode‐and‐forward relay systems with wireless energy harvesting

SummaryThis paper considers an underlay cognitive radio (CR) wireless network with the assistance of a two‐hop decode‐and‐forward (DF) relay node. Different from the conventional CR relay networks, in this paper, the relay node using power‐splitting (PS) techniques harvests wireless energy transmitted from the secondary base station (SBS) and, then, uses its harvested energy to forward the received signals to multiple secondary receive users (SRUs). Due to the highly mutual dependence of the transmission strategies at nodes on the system performance, the optimal design of signal processing at transceivers to efficiently handle the interference and energy constraints is crucial. This paper studies the jointly optimal design of the precoders, PS factors to maximize the minimum user rate under the transmit power, harvested energy, and interference power constraints. Owing to the nonlinearly and mutually coupled design matrix variables in both objective function and constraints, the joint design of the precoders and PS factors for the concerned problem is mathematically challenging. To tackle these difficulties, we devise the appropriate surrogate functions to recast the nonconvex optimization problem into the convex one. By using the minorization–maximization framework, an efficient iterative algorithm with provable convergence is developed by solving the convex optimization problem in each iteration. Numerical results are provided to evaluate the achievable user rate performance of the considered system and investigate the effects of the interference power thresholds at the primary receive users and the number of antennas at the SBS and the relay on the minimum achievable user rate.

Asynchronous Channel-Hopping Sequences With the Best Maximum-Time-to-Rendezvous and Period for Cognitive-Radio Wireless Networks

A new family of asynchronous channel-hopping (CH) sequences for cognitive-radio wireless networks (CRWNs) is constructed by a novel 2-D method. The new construction applies two different algorithms to create the columns and rows of a base matrix, which is mapped row-by-row to form the 1-D CH sequences. In addition to full degree-of-rendezvous, the new CH sequences have the shortest period and maximum-time-to-rendezvous and allow more flexible choices of period and number of licensed channels than their counterparts. While short period saves memory in small sensors and mobile devices, the new construction is shown to support the largest throughput with the fewest licensed channels (i.e., spectral resources) in practical CRWNs.

Two-Hop Transmissions in Asynchronous Channel-Hopping Cognitive Radio Wireless Networks With Buffer-Aided Relays

Due to physical constraints or channel impairments, direct (one-hop) communications among secondary nodes may not be possible in cognitive-radio wireless networks (CRWNs). In this letter, the rendezvous problems of two-hop transmissions using a relay node with buffer of different sizes in channel-hopping (CH) CRWNs are studied. A two-hop rendezvous protocol operating with suitable asynchronous CH sequences is proposed. A new performance metric, maximum time-to-rendezvous-with-relay (MTTR r ), and throughput are derived for different buffer sizes. The studies find that (i) both MTTR r and throughput improve as the buffer size increases but see no further improvement beyond a certain buffer size, and (ii) the proposed two-hop rendezvous model has only slight performance penalties as compared to the conventional (one-hop) counterpart.

A review on wireless multimedia cognitive radio networks

A review on wireless multimedia cognitive radio networks

A corner truncated fractal slot ultrawide spectrum sensing antenna for wireless cognitive radio sensor network

SummaryDue to the scarcity of the radio frequency spectrum, the emergent network sharing technique elicits the efficient use of licensed unutilized spectrum. Here, an ultra‐wideband (UWB) microstrip antenna is proposed for wireless cognitive radio sensor network (WCRSN). The antenna is uniquely designed for large spectrum scanning of channel vacancies in licensed frequency bands. Software‐defined radios (SDR) govern the algorithmic controls on spectrum sensing and channel interface using an appropriate antenna. The antenna comprises the effects of fractal slot patch and electromagnetic bandgap (EBG) ground structures on 12 × 18 × 1.6 mm3 FR4 (relative dielectric constant of 4.4) substrate. Circular polarization is achieved through corner truncation to make antenna orientation free in wireless sensing networks. The measured |S11| parameter offers 0.75‐ to 12‐GHz wide spectrum sensing with 2.51‐dBi average gain. The antenna is unique in compactness and includes lower edge bands of frequencies (0.75–3.1 GHz) along with UWB (3.1–12.0 GHz) for a very wide range scanning to utilize vacant channel opportunity in WCRSN through SDR. The proposed structure is experimented and validated for real‐time wideband scanning of the frequency spectrum within the operating limit as per the allotted FCC standard.

SDN‐enabled Cognitive Radio Network Architecture

In this study, a new network architecture based on the software-defined networking (SDN) approach is proposed for cognitive radio networks (CRNs). The proposed network architecture [software-defined cognitive radio (SDCR)] assumes the responsibilities of network resource management for CRNs and provides a dynamic spectrum management mechanism with an SDN controller. In this way, the dependency of network users on base stations is reduced in dynamic cognitive radio environments, and network performance is improved by delegating some of the management responsibilities to the controller. The performance analysis of the SDCR is carried out through the RIVERBED MODELER simulation software. End-to-end delays and packet loss rates for the primary network are investigated by selecting different offered loads for secondary users. In addition, for the equal and different packet sizes, primary network and SDCR throughput are examined and network performance is improved by using channel bonding technique. The results indicate that the SDCR outperforms the traditional CRN architecture, in terms of the throughput, and the proposed architecture can provide effective performance. Bit error rate parameter is investigated in the study and the energy consumption parameter of the SDCR is also compared with the cognitive radio wireless network.

Compact Corner Truncated Fractal Slot Antenna for Cognitive Radio Sensor Network

The cognitive radio (CR) opens new paradigms of opportunistic utilization of unused frequency spectrum through spectrum sharing. Dynamic spectrum access (DSA) provides an effective solution to channel congestion with the help of software-defined radio in cognitive radio networks (CRN). Software defined radio (SDR) offers manipulative wide spectrum sensing and reconfigurable transmission properties between licensed primary user (PU) and unlicensed secondary user (SU). The opportunistic spectrum sharing elicits the need for hardware compatibility from a common radiating antenna for extra-large band spectrum scanning. This paper proposes a novel compact antenna for wide spectrum sensing to utilize vacant channel opportunity in wireless cognitive radio sensor network (WCRSN). The antenna design comprises the combinational effects of fractal slots and electromagnetic bandgap structure on compact FR4 substrate 12 × 18 × 1.6 mm2. The circular polarization improves the feasibility of antenna for orientation-free scanning of spectrum through corner truncation. The novel antenna design exhibits large measured impedance bandwidth from 0.79 to 12.0 GHz compatible with Zigbee, Bluetooth, GPS, GSM, LoRa, WiFi and other UWB applications. The antenna offers average gain 2.59 dBi over entire operating frequency range and validates compatibility for spectrum sensing in WCRSN as per FCC standards.

Dynamic Interference Optimization in Cognitive Radio Networks for Rural and Suburban Areas

In this paper, we investigate the coexistence of cognitive radio networks on TV white spaces for rural and suburban connectivity. Although experimental models and laboratory measurements defined the maximum interference threshold for TV white space technologies for general use cases, our research found that in real wireless rural and suburban scenarios, severe interference to the broadcasting services might occur. This is particularly relevant when the traffic load of the telecom base stations (BSs) exceeds 80% of their maximum capacity. We propose a dynamic management algorithm for minimizing the interference, based on a centralized access control architecture for cognitive radio wireless networks. In an experimental emulation for assessing the impact of cognitive radio interference on the broadcasting service’s QoE, our method reduced the perceived video distortion by the broadcasting users by at least 50% and 27.5% in a rural and suburban scenario, respectively, while the spectrum usage is increased by just 8%.

MRCSC: A cross-layer algorithm for joint Multicast Routing, Channel selection, Scheduling, and Call admission control in multi-cell multi-channel multi-radio cognitive radio wireless networks

This paper addresses the problem of joint multicast routing, channel selection, scheduling, and call admission control in multi-cell multi-channel multi-radio cognitive radio wireless mesh networks. The applied model relies on the QoS sessions, where each one is expressed with a bandwidth requirement. We propose a cross-layer algorithm named “Multicast Routing, Channel selection, Scheduling, and Call admission control (MRCSC)”. The proposed scheme, considering wireless broadcast advantage, channel/radio diversity, and spatial reuse, uses both intra- and inter-cell relaying to create multicast trees with a specific bandwidth. MRCSC considers both inter-flow and intra-flow interferences. It adopts an efficient collision-free mechanism to greedily schedule different multicast transmission in the network. As an advantage, considering the multi-radio technology, MRCSC allows the nodes to simultaneously send/receive data on different available non-overlapping channels. Numerical results of our comprehensive simulations confirm the efficiency of the MRCSC algorithm in terms of the number of transmissions, stability, and multicast period.

A divide-and-conquer based improved genetic algorithm for network selection in heterogeneous wireless network

Developing and using wireless network is a trend to serve passengers in aircraft cabins. Cognitive radio technology can be used in aircraft cabin wireless environment to solve the spectrum resource scarcity problem. Heterogeneous network access issue should be noticeable in cognitive radio wireless networks. In this paper, an improved genetic algorithm (GA) based on divide-and-conquer is proposed to handle this problem. The proposed approach is compared with original GA, particle swarm optimisation (PSO) algorithm and tabu search (TS) algorithm. The simulation results prove that the proposed method can obtain greater bandwidth with higher efficiency.

Performance Analysis of a New MAC Protocol for Wireless Cognitive Radio Networks

In this study, network performance analysis of a newly proposed cognitive radio wireless network (CRWN) medium access control (MAC) protocol is investigated in order to improve the performance of wireless cognitive radio networks (CRNs). Several MAC protocols have been used in the literature in order to increase the performance of wireless CRNs. In this context, a cognitive radio based MAC protocol is proposed, which is also a solution to the needs of wireless CRNs with high performance results. We propose an autonomous control strategy that recognizes both the primary network and the CRN environment considering the service quality requirements of the wireless CRN environment. Simulation of the network environment is performed with Riverbed Modeler software for more realistic performance evaluation. By selecting various workloads for secondary users, the analysis of different network performance parameters such as throughput ratios, end-to-end delays, packet loss ratios, bit error rates, and energy consumptions reveal the originality of our study. In addition, Slotted Aloha, TDMA, and CSMA/CA based MAC protocols for CRNs used in different studies in the literature are compared with CRWN. As a result, proposed protocol is given about 40% higher performance than Slotted Aloha in terms of throughput and about 36% higher performance than TDMA in terms of delay. Moreover, the proposed CRWN consumes less energy than CSMA/CA.

Performance analysis of radio spectrum for cognitive radio wireless networks using discrete time Markov chain

Cognitive radio (CR) arises as an important technique for wireless network with the aim to provide better utilization of radio spectrum, which is being utilized sporadically in some areas. IEEE 802.22 wireless regional area network (WRAN) is the first standard for CR technology designed to opportunistically utilize the unused or under-utilized TV bands. A WRAN cell normally consists of a number of customer premises equipments (CPEs)/CR users and a base station (BS) having master/slave architecture. When a CPE is powered on, it first attempts to associate with the BS. In this paper, a discrete time Markov chain model (DTMC) is presented to show the association process of CPEs with the BS. To the best of our knowledge, this paper is the first in which DTMC Model is analyzed and investigated for WRAN. Using this model, various parameters such as association time, expected return time to the respective backoff stage, first passage time, etc., are derived. Finally, the evaluation results are provided to analyze the system's performance.

Tradeoff Analysis between Spectral and Energy Efficiency Based on Sub-Channel Activity Index in Wireless Cognitive Radio Networks

In recent years, there has been a rapid evolution of wireless technologies that has led to the challenge of high demand for spectral resources. To overcome this challenge, good spectrum management is required that calls for more efficient use of the spectrum. In this paper, we present a general system, which makes a tradeoff between the spectral efficiency (SE) and energy efficiency (EE) in the cellular cognitive radio networks (CCRN) with their respective limits. We have analyzed the system taking into account the different types of power used in the CCRN, namely the spectrum detection power (Zs) and the relay power (Zr). Optimal policy for emission power allocation formulated in the function of sub-channel activity index (SAI) as an optimization problem in order to maximize spectrum utilization and minimize the energy consumption in the base station of the secondary system energy consumption, is subject to different constraints of the main user system. We also evaluate the collaborative activity index of the sub-channel describing the activity of the primary users in the CCRN. The theoretical analyses and simulation results sufficiently demonstrate that the SE and EE relationship in the CCRN is not contrary and thus the achievement of optimal tradeoff between SE and EE. By making a rapprochement with a cognitive cellular network where SBSs adopts an equal power allocation strategy for sub-channels, the results of our proposed scheme indicate a significant improvement. Therefore, the model proposed in this paper offers a better tradeoff between SE and EE.