• Journal of Engineering Education Research
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• v.18 no.6
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• pp.11-17
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• 2015

This study examined the moderating effect of engineering design self-efficacy on the relationship between cognitive team diversity and team creativity. For this study, 377 mechanical engineering students in engineering design classes were included in the analysis. The results showed that both cognitive team diversity and engineering design self-efficacy were positively correlated with team creativity. The analysis of moderating effect indicated that engineering design self-efficacy further reinforced the positive relationship between cognitive team diversity and team creativity. Finally, implications and limitations of this study were explored.

• Journal of Technology Innovation
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• v.13 no.1
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• pp.141-167
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• 2005

The purpose of this study is to present the model of performance in new product R&D project team, from the perspective of the problem solving. The quality and commitment of the problem solutions in R&D project team depend on the team's cognitive diversity and affective acceptance. The higher cognitive diversity is, the higher quality of solutions is. And more affective acceptance is, more commitment to the problem solving is. The environmental maturity of team, and quality and commitment of problem solutions in R&D project teams are supposed to relate to the performance of research and development.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.3
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• pp.179-185
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• 2009

Cognitive radio (CR), which is proposed as a technology that utilizes the frequency resources effectively, has studied to relive scarcity of the frequency resources. CR provides opportunistically unused frequency to the secondary user when the primary user is not detected. Spectrum sensing is the most important technology to detect primary user. However, in the wireless channels, according to the effect of multipath fading channel, spectrum sensing performance is compromised. Therefore, in this paper, we apply diversity scheme that is a useful technique for combating multiple fading in wireless communications. There are several classes of diversity scheme, which are time diversity, antenna diversity, muitipath diversity, frequency diversity, and so on. In this paper, we adopt antenna diversity that is a kind of space diversity. By using the proposed method, we can overcome fading effect and improve spectrum sensing performance.

• International Journal of Computer Science & Network Security
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• v.24 no.2
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• pp.95-100
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• 2024

Cyclic Delay Diversity (CDD) is a diversity scheme used in OFDM-based telecommunication systems, transforming spatial diversity into frequency diversity and thus avoiding intersymbol interference without entailing the receiver to be aware of the transmission strategy making the signal more reliable achieving full diversity gain in cooperative systems. Here the analyzation of the influence of CDD-SC scheme in Cognitive Radio Network (CRN) is done with the challenge of overcoming the complication called channel estimation along with overhead in CNR. More specifically, the closed-form expressions for outage probability and symbol error rate are divided under different frequencies among independent and identically distributed (i.i.d.) frequency selective fading channel model i.e., the signal is divided into different frequencies and transmitted among several narrow band channels of different characteristics. It is useful in the reduction of interference and crosstalk. The results reveal the diversity order of the proposed system to be mainly affected by the number of multipath components that are available in the CNR.

• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.99-103
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• 2010

Motivated by recent works on spectrum-sharing systems, this paper investigates the effects of transmit diversity on the peak interference power limited cognitive radio(CR) networks. In particular, we derive the ergodic and outage capacities of a spectrum-sharing system with multiple transmit-antennas. To derive the capacities, peak interference power constraint is imposed to protect the primary receiver. In a CR transmitter and receiver pair with multiple antennas at the transmitter side, the allowable transmit power is distributed over the transmit-antennas to achieve transmit diversity at the receiver. We investigate the effect of this power distribution when a peak interference power constraint is imposed to protect the primary receiver. We show that the transmit diversity does not improve the ergodic capacity compared to the single-antenna system. On the other hand, the transmit diversity significantly improves the outage capacity. For example, two transmit-antennas improve the outage capacity 10 times compared to the single-antenna with a 0 dB interference constraint.

• Journal of electromagnetic engineering and science
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• v.9 no.4
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• pp.194-201
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• 2009

In this paper, a new spectrum sensing method based on energy detection is proposed and analyzed in a cognitive radio(CR) system. We employ a delay diversity receiver for sensing the primary user's spectrum with reasonable cost and complexity. Conventional CR with the receiver equipping multiple antennas requires additional hardware and space for installing multiple antennas in accordance with increase in the number of antennas. If the number of antennas increases, detection probability as well as hardware complexity and cost rise. Then, it is difficult to make a primary user detector practically. Therefore, we adopt a delay diversity receiver for solving problems of the conventional spectrum detector utilizing multiple antennas. We derive analytical expressions for the spectrum sensing performance of the proposed system. From the simulation results, it is demonstrated that the primary user detector with the delay diversity receiver has almost half the complexity and shows similar or improved performance as compared with that employing multiple antennas. Therefore, the proposed spectrum sensing structure can be a practical solution for enhancing the detection capacity in CR system operations. The results of this paper can be applied to legacy CR systems with simple modifications.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1279-1300
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• 2017

In the interweave cognitive networks, the interference from the primary user degrades the performance of the cognitive user transmissions. In this paper, we propose an adaptive cooperation scheme in the interweave cognitive networks to improve the performance of the cognitive user transmissions. In the proposed scheme for the bidirectional communication of two end-source cognitive users, the bidirectional communication is completed through the non-relay direct transmission, the one-way relaying cooperation transmission, and the two-way relaying cooperation transmission depending on the limited feedback from the end-sources. For the performance analysis of the proposed scheme, we derive the outage probability and the finite-SNR diversity multiplexing tradeoff (f-DMT) in a closed form, considering the imperfect spectrum sensing, the interference from the primary user, and the power allocation between the relay and the end-sources. The results show that compared with the direct transmissions (DT), the pure one-way relaying transmissions (POWRT), and the pure two-way relaying transmissions (PTWRT), the proposed scheme has better outage performance. In terms of the f-DMT, the proposed scheme outperforms the full cooperation transmissions of the POWRT and PTWRT.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.4
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• pp.49-69
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• 2010

In this paper, we propose a class of spectrum sensing schemes for cognitive radio with receive diversity. By considering the generalized likelihood ratio test detector in each branch and exploiting non-linear diversity combining strategy, the proposed scheme exhibits reasonable performance for spectrum sensing even in the environment of heavier-tailed noise. From the results of analysis and computer simulations, it is observed that the proposed scheme provides significant performance gain and performance stability over the conventional schemes, especially in impulsive noise environment.

• Knowledge Management Research
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• v.4 no.2
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• pp.1-18
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• 2003

Team-members may have diverse backgrounds and characteristics and such diversity is getting increased in teams in terms of demographics(gender, age, and educations) and capabilities(knowledge, skills, and experiences). A meta-analysis of the last 40 years studies, however, concluded that diversity in teams does not have the consistent main effect on team performances. On the other hand, according to theories of selection and socialization, similarity in values, backgrounds, and experiences buttress the positive and effective working environment. Therefore, we conduct an empirical study in favor of similarity in work teams for the sake of team effectiveness. We investigated the importance of the similarity of team-members on IT team effectiveness. Two aspects of similarity, demographic and cognitive, were considered together. The shared mental model(SMM) was introduced as the representative construct for the cognitive similarity. We found that SMM is more important than the demographic similarities on team effectiveness.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.12
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• pp.3003-3017
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• 2013

In this paper, we investigate the outage performance of a cognitive relay network. We consider mutual interference in an independent, non-identically distributed Nakagmai-m fading environment. We first derive the close-form outage probability expression, which provides an efficient means to evaluate the effects of several parameters. This allows us to study the impact of several parameters on the network's performance. We then derive the asymptotic expression and reveal that the diversity order is strictly determined by the fading severity of the cognitive system. It is not affected by the primary network. Moreover, the primary network only affects the coding gain of the cognitive system. Finally, Monte Carlo simulations are provided, which corroborate the analytical results.