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Cognitive radio (CR) has been recognized as future prospect for efficient and dynamic allocation of bandwidth among users of which dynamic spectrum access is an important aspect focusing on identification and opportunistic utilization of vacant spectrum in television broadcasting licensed bands, known as television white spaces (TVWS). TVWS has bee...
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... Using network analysis on keywords can also reveal the various tracks a study on a particular topic takes. This could be the first step in a student's or researcher's journey (Singh et al. 2018). Figure 8 depicts the keyword network analysis, while Fig. 9 is a word cloud comprising the most frequently used words in the corpus (2022). ...
Frauds accounted for significant losses in the financial sector and emerged as the industry’s biggest challenge. Companies invest significant amounts to prevent such fraud. It has been reported that 63.6% of the financial institutions that use Automated Fraud prevention methods successfully prevented frauds before their occurrence. Some estimations suggest that 80% of specialists are confident in cutting down fraud using Artificial Intelligence (AI)-based platforms. Several research studies have also administered AI-based techniques for fraud prevention. This study takes a systematic literature review approach to uncover the emerging areas of fraud detection using AI. The authors have analyzed 241 research articles published in the last 20 years. The Scopus database was the source of the articles in the literature review. The meta-analysis and network analysis were carried out, and the output shows the up trend of this research domain. Author-coauthor network collaboration is analyzed using the VOSviewer tool. K-means clustering was performed to identify the critical research domain, and future research areas were also identified. This research will act as a reference for future scholars who want to perform analysis on the application of AI techniques in financial fraud detection and prevention. We finally conclude the study by identifying the scope of future research and will be a value addition for financial fraud researchers.
... An error in channel estimation affects the symbol detection accuracy. Singh et al. [24] surveyed physical layer (PHY) and cognitive radio features of OFDM. The practical MIMO is used to improve the throughput of wireless regional area networks (WRAN). ...
Recent mobile telecommunication systems are using multiple-input multiple-output system (MIMO) collective with the orthogonal frequency division multiplexing (OFDM), which is well-known as MIMO-OFDM, to offer robustness and higher spectrum efficiency. The most important challenge in this scenario is to achieve an accurate channel estimation to identify the information symbols once the receiver must have the channel state information to balance and process the received signal. Hence, an effective technique is introduced by proposing the Taylor-least square error algorithm (TLSE) to improve the performance of the MIMO-OFDM system in multimedia applications. In addition, the user admission control is done in multi user-MIMO (MU-MIMO) system using the priority-based scheduling based on Dolphin-rider optimization (DRO) algorithm that is integrated within the space–time block code (STBC) STBC-MIMO-OFDM system for efficient power allocation to ensure the energy efficiency. The DRO is the integration of rider optimization algorithm (ROA) and Dolphin Echolocation (DE). Here, channel estimation is done using the novel optimization algorithm, termed TLSE, which is designed by modifying LSE with the Taylor series. Moreover, the fitness parameters, such as power, priority, throughput, and Proportionally Fair, are computed. The experimentation is conducted in different fading environments with three modulation schemes, binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), and quadrature amplitude modulation (QAM) with the performance metrics, namely bit error rate (BER) and throughput. The developed TLSE + DRO (QAM) outperformed other methods with minimal BER of 0.0001 based on channel-2 and maximal throughput of 0.9965 with respect to channel-1.
... Aloha, Slotted Aloha, and CSMA MAC protocols are in contention class. Several studies related to Pure Aloha, Slotted Aloha [8,[15][16][17][18], TDMA [19][20][21][22], OFDM [23][24][25][26][27][28][29], CDMA [30] and CSMA [3,[31][32][33][34][35][36][37] MAC protocols have been found in the literature. Unlike in the literature, this study focuses on a new MAC protocol which is suitable for wireless CR network environment. ...
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.
In order to implement the interweave cognitive radio solutions, the research for finding sparsely utilized spectrum bands has revealed the VHF and UHF television broadcast bands, known as television white spaces (TVWS) as the foremost candidate. The TVWS quantification and throughput analysis conducted via several measurement attempts and field trials uncover various facets of the TVWS spectrum measurement. Consequently, the conclusions obtained may be processed to get a statistical knowledge about spectrum availability in a particular geographic region and hence utilized for spectrum management. This paper explores inherent methodologies used for TVWS assessment and provides a comprehensive overview of the TVWS regulatory norms, results obtained by TVWS measurement campaigns and field trials conducted worldwide. In addition, research issues, implementation challenges and future directions for TVWS measurement procedure are highlighted.
