• Title/Summary/Keyword: diversity

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Transmit Diversity Using Windowing Scheme in OFDM System (OFDM 시스템에서 윈도윙 기법을 이용한 송신 다이버시티)

  • Kim, Yong-June;Rim, Min-Joong;Lim, Dae-Woon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.9A
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    • pp.871-877
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    • 2007
  • In this paper, we propose a new transmit diversity scheme using window functions in orthogonal frequency division multiplexing (OFDM) system. Transmit diversity of the scheme is varied with window functions and the condition of the window function to maximize transmit diversity is derived. The proposed scheme can be considered as a generalization of the diversity schemes such as cyclic delay diversity (CDD), orthogonal transmit diversity (OTD), and frequency switched transmit diversity (FSTD).

The Fabrication and Performance Estimation of Circularly Polarization Diversity System for Multipath Fading Reduction (다중경로페이딩 경감을 위한 원편파 다이버시티 시스템 제작 및 성능 평가)

  • 이주현;김판신;안재성;김태홍;고연화;김흥진;하덕호
    • Proceedings of the IEEK Conference
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    • pp.609-612
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    • 2003
  • For combating multipath fading in wireless radio environment, diversity schemes is useful. In this paper, for performance improvement of polarization diversity system, we analyzed a two-branch polarization diversity at the receiving end of a mobile link when the transmitter emits a circularly polarized wave. And In order to calculate the correlation coefficient considering the XPD(cross polarization discrimination) between the received signals for the two diversity branches, a simple theoretical model of circular polarization diversity is adopted and calculate correlation coefficient. From the analysis results, it is seen that the correlation coefficient of circular polarization diversity evaluated by the XPD is less than that of vertical polarization diversity. And also, we designed and fabricated circular polarization diversity system with microstrip antenna. we analyzed data measured in indoor NLOS environment using fabricated circular polarization diversity system. From the measurement results, it is clearly seen that the diversity effect of circular polarization diversity system is higher 3dB than vertical polarization diversity system.

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Analysis on the Impact of Multiple-Antenna Transmit Schemes on Multiuser Diversity

  • Lee, Myoung-Won;Mun, Cheol;Yook, Jong-Gwan
    • Journal of electromagnetic engineering and science
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    • v.6 no.4
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    • pp.222-228
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    • 2006
  • In this paper, the performance of a multiuser diversity system combined with a multi-element transmit antenna system is analyzed under the assumption of independent Rayleigh fading. A measure of system .level performance is an average channel capacity as a function of the number of users and antennas. Average channel capacity is obtained from the instantaneous signal-to-noise ratio(SNR) distribution combined by both transmit diversity(TD) at each link and multiuser diversity at system level. Numerical results show that closed-loop antenna techniques provide an additional gain with multiuser diversity system due to array gain, even though space diversity gain reduces multiuser diversity gain. On the other hand, the space-time block coding(STBC) that provides full order space diversity gain only has a destructive influence on multiuser diversity.

Workforce Diversity: A Springboard for Employee Productivity and Customer Experience

  • MAKUDZA, Forbes;MUCHONGWE, Nevermind;DANGAISO, Phillip
    • The Journal of Industrial Distribution & Business
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    • v.11 no.10
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    • pp.49-58
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    • 2020
  • Purpose: The purpose of this study was to examine the differential effect of workforce diversity on employee productivity and its subsequent impact on customer experience. Research design, data and methodology: A once-off cross-sectional research design was used in this study where the Zimbabwean civil service was targeted. Randomization was used to collect 324 validated responses. The study focused on both primary (age and gender) and secondary (education and political affiliation) dimensions of workforce diversity. Results: The results were confirmatory that workforce diversity is a significant predictor of employee productivity (β = 0.668, P < 0.05), at the same time employee productivity holds explanation to customer experience by 37%. Results also revealed that gender diversity, educational diversity and political diversity were significant determinants of workforce diversity (P < 0.05). However, the study established that age diversity was not a significant factor in enhancing employee productivity (P > 0.05). Conclusions: The study concluded that workforce diversity is a powerful tool in enhancing both customer experience and employee productivity. As such, the latter can be augmented through shrewd workforce diversity practices as championed by management. To that end, the study recommends the development of a workforce diversity framework which promotes inclusivity.

The Effects of Perception Levels of Diversity on Team Performance: Moderating Effects of Conflict (다양성 지각 정도가 팀의 성과에 미치는 영향: 갈등의 조절효과를 중심으로)

  • Yun, Jun Hee;Shin, Ho-Chul
    • Journal of the Korean Society for Quality Management
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    • v.41 no.2
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    • pp.289-300
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    • 2013
  • Purpose: The results of prior studies investigating main effects between diversity and team performance are neither clear nor consistent. This study seeks to provide more evidence for a direct link between these two. The present study also attempts to close a gap in the literature by examining conflict as a moderator of the relationship between diversity and team performance. Methods: As suggested by Williams and O'Reilly(1998), this study examines the effects of perception levels of three specific types of diversity (social category diversity, value diversity, and informational diversity) and two contextual moderators (task conflict and relationship conflict) on team performance. Results: The results show that perception levels of all three types of diversity are significantly related to team performance in the current sample of 313. Results also indicate that relationship conflict significantly interacted with the perception levels of diversity in relating to team performance. Results for task conflict, however, fails to support the hypothesis. Conclusion: The results suggest that the effects of diversity on team functioning depend on how diversity is perceived by team members, rather than actual diversity seen by team members. Theoretical and practical implications are reviewed, and limitations of the study and suggestions for future research are addressed.

Performance Analysis of Angle Time Transmit Diversity in Urban Area (도심환경에서 각도-시간 송신다이버시티의 성능분석)

  • Park, Byeong-Hoon
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.60 no.4
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    • pp.200-205
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    • 2011
  • In multipath fading channel, diversity is essential to mitigate the impairments. In this paper, we have proposed the angle diversity scheme called ATTD(Angle Time Transmit Diversity) instead of Alamouti's STTD(Space Time Transmit Diversity) and have analyzed the performance of the proposed scheme when signal powers caused by the transmission to different angles are different. Based on it, we have measured the wireless vector-channel in the urban area, which has lots of high-story buildings, using the data collected from the 8 by 4 smart array antenna system that we made. According to the measured data, the received signals from different angles have different signal powers. Our performance analysis results show that the proposed scheme has better performance than the space diversity scheme when the received path signal power is at least -7dB compare to the strongest path signal power.

Circular Polarization Diversity in Indoor Wireless Mobile Environments

  • Ha, Deock-Ho;Ko, Yeon-Hwa;An, Jae-Sung;Kim, Tai-Hong
    • Journal of electromagnetic engineering and science
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    • v.4 no.3
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    • pp.128-136
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    • 2004
  • In this paper,. with the aim of achieving the expected performance improvement for a polarization diversity system, we analyzed two-branch polarization diversity at the receiving end of a mobile link which a transmitter emits circularly polarized wave. In this analysis, to calculate the correlation coefficient considered by XPD(cross polarization discrimination) between the two received signals, a simple theoretical model of circular polarization diversity is adopted. From the analysis results, it is clearly seen that the correlation coefficient of circular polarization diversity evaluated by the XPD is less than that of conventional linear polarization diversity. And also, we designed and implemented a circular polarization diversity system with micro-strip antenna. By using the circular polarization diversity system, we analyzed the measured data in indoor NLOS(Non-Line-Of-Sight) environments. From this analysis results, it is also clearly seen that the diversity effect of circular polarization diversity system shows better performance compared to the conventional linear diversity system by about 3 dB high.

The Analysis of Protection Ratio and Its Effect of Interference-to-Noise Ratio for Digital Microwave System with Diversity

  • Suh Kyoung-Whoan;Jang Won-Gyu
    • Journal of electromagnetic engineering and science
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    • v.6 no.3
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    • pp.189-195
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    • 2006
  • In this paper, the derivation of the protection ratio for the digital microwave system with diversity is newly suggested for a basic guidance of initial planning for frequency coordination, and computational results are presented for an actual radio frequency band. The net filter discrimination has been also examined to see the effect of the adjacent channel protection ratio caused by adjacent channel interference. In addition, the protection ratios for the space or frequency diversity system are analyzed in terms of diversity improvement factors to find out an equivalent allowable noise-to-interference ratio (N/I) from degraded fade margin. According to results for 6.2 GHz system, with the space diversity of 25 m distance between antennas or the frequency diversity of ${\Delta}f/f=0.05$, under 64-QAM and 60 km at BER $10^{-6}$, the protection ratio can be greatly reduced in comparison to the non-diversity system. So, assuming that only the same protection ratio as the non-diversity system is kept, it is shown that the system with diversity may get more interference level of N/I allowing from 9.0 to - 5.9 dB or from 6.0 to - 4.3 dB for the space or frequency diversity. In consequence, it is concluded that the diversity system is more robust or tolerable for interferences or fades, which may play an important role in overcoming N/I to some extent.

Frequency Diversity using Orthogonal Encoder and Decoder in the OFDM Transmission with No Transmission (비전송을 채택한 OFDM 전송방식에서의 직교 부호화 및 복호화를 이용하는 주파수 Diversity)

  • 고예윤;강홍구;조규섭
    • Proceedings of the IEEK Conference
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    • pp.19-22
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    • 2003
  • 본 논문에서는 비전송을 갖는 OFDM 전송을 위한 직교 부호화기와 복호화기를 사용하는 새로운 주파수 diversity 기술을 제안하였다. 기존의 주파수 diversity 방식이 하나의 데이터를 여러 개의 부반송파들을 이용하여 전송하는 반면, 제안한 주파수 diversity 방식은 직교적으로 부호화된 여러 데이터를 여러 개의 부반송파를 통하여 전송한다. 따라서, 제안한 방식은 하나의 데이터가 여러 부반송파를 통하여 전송되므로, diversity 에 의한 성능의 이득을 유지하면서도 하나의 부 반송파에 직교적으로 혼합된 또 다른 전송 심벌을 전송하므로 기존 주파수 diversity 의 단점인 주파수 대역폭의 비효율성을 만들지 않는 장점을 갖게 된다.

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Determining the Optimum Brands Diversity of Cheese Using PSO (Case Study: Mashhad)

  • Dadrasmoghadam, Amir;Ghorbani, Mohammad;Karbasi, Alireza;Kohansal, Mohammad Reza
    • Industrial Engineering and Management Systems
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    • v.15 no.4
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    • pp.318-323
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    • 2016
  • In the current study, factors affecting cheese brands products in grocery stores were evaluated with an emphasis on diversity. The sample data were collected from Noushad and Pegah Milk Industry in 2015 and data were extracted, reviewed, and analyzed from 435 grocery stores in Mashhad using seemingly unrelated regression model and particle swarm optimization algorithm. Results showed that optimum amount of Kalleh product diversity is higher than other competitors in the market, and Kalleh UF diversity is 100 to 250 grams, and Kalleh UF diversity with weight of 300 to 500 grams is more than other modes of diversity, and Kalleh brand must remove tin cheese from the market. Sabah Brand also should eliminate its glass and creamy diversity from market, UF diversity is mostly welcomed in market.