414 research outputs found

    Indefinite origin: decentralizing knowledge

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    The RISD Digital Commons notes that “graduate education is focused on producing original contributions to a field, based on research and advance practice. What is collaborative thesis, and what value does it bring to the process? Indefinite Origin, is a thesis advocating for knowledge to be decentralized and treated as a shared resource. Deviating from a focus on originality, it engages in the creation of knowledge as a collaborative effort. Design flexibility is practiced through intellectual humility, negotiating methodologies and welcoming chance. This thesis explores ideas from Furtherfield’s Do-It-With-Other (DIWO) or Do-It-Together (DIT)4 philosophies that promote synergy around commons5, cultural and natural resources that are accessible to all members of society

    Self-optimized Coverage Coordination in Femtocell Networks

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    This paper proposes a self-optimized coverage coordination scheme for two-tier femtocell networks, in which a femtocell base station adjusts the transmit power based on the statistics of the signal and the interference power that is measured at a femtocell downlink. Furthermore, an analytic expression is derived for the coverage leakage probability that a femtocell coverage area leaks into an outdoor macrocell. The coverage analysis is verified by simulation, which shows that the proposed scheme provides sufficient indoor femtocell coverage and that the femtocell coverage does not leak into an outdoor macrocell.Comment: 16 pages, 5 figure

    Latest Overseas Policy on Coronavirus Disease 2019 Vaccination for Children Aged 5 to 11

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    In Korea, children aged 5 to 11 have been vaccinated against coronavirus disease 2019 (COVID-19) from March 2022. Due to this age group not being at a high risk of developing severe COVID-19 symptoms, each major country has different, circumstance dependent, immunization policies for children. In this review, the COVID-19 vaccination policies for 5–11 years old children in major countries were reviewed and considerations were presented for Korea, where children 5–11 years old are starting to get vaccinated against COVID-19

    A Complexity Reduced ML Detector on OFDM-CDM Systems in Mobile Channel

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    Orthogonal frequency-division multiplexing (OFDM) is one of the most promising techniques for the 4-th generation mobile system. When the OFDM system is applied to cellular environment, it is required to make the transmission scheme robust to other-cell interference (OCI). The use of code division multiplexing (CDM) has been considered to mitigate the OCI in OFDM systems. In cell boundary, it is desirable to design OFDM-CDM transceiver scheme to reduce the effect of OCI. In this paper, we consider transceiver schemes for cell boundary users in the OFDM-CDM downlink. We propose a simplified maximum likelihood (ML) detection scheme that can nearly achieve full ML detection performance. In addition, a new spreading code is proposed for BPSK modulation, yielding a receiver gain of about 1dB regardless of detection schemes. Finally, the performance of the proposed schemes is verified by computer simulation

    A Framework Design for the Next-Generation Radio Access System

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    Extensive use of the Internet and huge demands for multimedia services via portable devices require the development of packet-based radio access systems with high transmission efficiency. Advanced radio transmission technologies have recently been proposed to achieve this challenging task. However, few researches have been reported on the design of an integrated system that can efficiently exploit the advantages of these transmission technologies. This paper considers the design of a packet-based cellular system for next-generation radio access. We propose a novel system framework that can incorporate various advanced transmission technologies such as link adaptation, opportunistic packet scheduling, channel coding, and multiantenna techniques. For efficient use of these technologies together, we first investigate the interoperability between these technologies by proposing a so-called cause and effect analysis. Based on this investigation, we design a differentiated-segments-based orthogonal frequency-division multiplexing system, called DiffSeg, to accommodate heterogeneous operating conditions in a seamless manner. Simulation results show that the proposed DiffSeg system can provide a nearly optimum performance with flexible configuration in a wide range of wireless channel conditions

    Other-Cell Interference Reducing Resource Allocation in OFDM-Based Asynchronous Cellular Systems

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    Orthogonal frequency division multiplexing (OFDM) is considered as one of the most promising techniques for next-generation wireless access systems. However, it may suffer from the so-called other-cell interference (OCI) in cellular environments. In this paper, we consider a novel resource allocation scheme to reduce the OCI in OFDM-based asynchronous cellular systems. The proposed scheme can reduce the OCI by exploiting repetitive properties of cyclic prefix of OFDM symbol and asynchronous properties between the user and the base stations in other cells. The proposed scheme can be applied to various types of OFDMbased systems such as orthogonal frequency division multiple access (OFDMA) and multicarrier code division multiple access (MC-CDMA) systems. Simulation results show that the proposed scheme can reduce the OCI by nearly up to 1 dB compared to conventional schemes, yielding an increase of the throughput of about 15% near the cell boundary in OFDM-based asynchronous cellular environments

    Determination of bit-rate and sensitivity limits of an optimized p-i-n/HBT OEIC receiver using SPICE simulations

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    The sensitivity of an OEIC receiver depends essentially on the physical sources of device and circuit noise referred to its input, provided that the inter-symbol interference (ISI) makes no significant contribution. For well designed receivers, the latter situation can be realized only at an optimum bandwidth (f3 dB-opt) for a given bit rate (B) or vice versa. In this paper, we have determined the relationship between the bit rate and the 3-dB bandwidth for negligible and pre-set levels of ISI for an optimized p-i-n/HBT transimpedance receiver with adjustable bandwidth.We have used the SPICE simulations in the frequency domain to determine the effect of device and circuit noise, and the SPICE transient analysis to determine the effect of ISI on the sensitivity. The ratio f3 dB-opt=B has been found to vary from 0.65 to 0.45 when B changes from 10 to 20 Gbps for the OEIC receiver used.This work was supported by the Korean Science and Engineering Foundation under Grant 94-X-0026, by the KAIST OptoElectronics Research Center (OERC), and also by the U.S. National Science Foundation under Grant ECS-9541739 (INT-9412658). The work of S. J. Kim was supported in part by the SeoAm Scholarship Foundation
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