The Experts below are selected from a list of 101979 Experts worldwide ranked by ideXlab platform
Sae-Woong Bahk - One of the best experts on this subject based on the ideXlab platform.
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Multichannel Random Access in OFDMA wireless networks
IEEE Journal on Selected Areas in Communications, 2006Co-Authors: Young-june Choi, Suho Park, Sae-Woong BahkAbstract:Orthogonal frequency-division multiple Access (OFDMA) systems are considered promising candidates for implementing next-generation wireless communication systems. They provide multiple channels that can be Accessed via Random Access schemes. However, traditional Random Access schemes could result in an excessive amount of Access delay. To address this issue, we develop a fast retrial scheme that is based on slotted Aloha and exploits the structure of OFDMA. A salient feature of this scheme is that when collisions occur instead of retrials occuring Randomly in time, they occur Randomly in frequency, i.e., the scheme Randomly selects the subchannels for retrial. To further achieve fast Access, retrials are designed to follow the 1-persistent type, i.e., no exponential backoff. To achieve the maximum throughput, we limit the maximum number of allowed retrials according to the load condition. We also consider the issue of designing for an appropriate reuse factor for Random Access channels in order to overcome the intercell interference problem in OFDMA multicell environments. Our finding is that full sharing, i.e., a reuse factor of one, performs best for given Random Access channels. Through analysis and simulation, we confirm that our fast retrial algorithm has the advantage of high throughput and low Access delay, and the full sharing policy for Random Access channels shows high throughput as well as low collision.
James M Tour - One of the best experts on this subject based on the ideXlab platform.
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molecular Random Access memory cell
Applied Physics Letters, 2001Co-Authors: Mark A Reed, Jia Chen, Adam M Rawlett, David W Price, James M TourAbstract:Electronically programmable memory devices utilizing molecular self-assembled monolayers are reported. The devices exhibit electronically programmable and erasable memory bits compatible with conventional threshold levels and a memory cell applicable to a Random Access memory is demonstrated. Bit retention times >15 min have been observed.
Young-june Choi - One of the best experts on this subject based on the ideXlab platform.
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Multichannel Random Access in OFDMA wireless networks
IEEE Journal on Selected Areas in Communications, 2006Co-Authors: Young-june Choi, Suho Park, Sae-Woong BahkAbstract:Orthogonal frequency-division multiple Access (OFDMA) systems are considered promising candidates for implementing next-generation wireless communication systems. They provide multiple channels that can be Accessed via Random Access schemes. However, traditional Random Access schemes could result in an excessive amount of Access delay. To address this issue, we develop a fast retrial scheme that is based on slotted Aloha and exploits the structure of OFDMA. A salient feature of this scheme is that when collisions occur instead of retrials occuring Randomly in time, they occur Randomly in frequency, i.e., the scheme Randomly selects the subchannels for retrial. To further achieve fast Access, retrials are designed to follow the 1-persistent type, i.e., no exponential backoff. To achieve the maximum throughput, we limit the maximum number of allowed retrials according to the load condition. We also consider the issue of designing for an appropriate reuse factor for Random Access channels in order to overcome the intercell interference problem in OFDMA multicell environments. Our finding is that full sharing, i.e., a reuse factor of one, performs best for given Random Access channels. Through analysis and simulation, we confirm that our fast retrial algorithm has the advantage of high throughput and low Access delay, and the full sharing policy for Random Access channels shows high throughput as well as low collision.
Mark A Reed - One of the best experts on this subject based on the ideXlab platform.
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molecular Random Access memory cell
Applied Physics Letters, 2001Co-Authors: Mark A Reed, Jia Chen, Adam M Rawlett, David W Price, James M TourAbstract:Electronically programmable memory devices utilizing molecular self-assembled monolayers are reported. The devices exhibit electronically programmable and erasable memory bits compatible with conventional threshold levels and a memory cell applicable to a Random Access memory is demonstrated. Bit retention times >15 min have been observed.
L.-m. Duan - One of the best experts on this subject based on the ideXlab platform.
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Experimental realization of 105-qubit Random Access quantum memory
Nature Publishing Group, 2019Co-Authors: N. Jiang, W. Chang, S. Zhang, L.-m. DuanAbstract:Abstract Random Access memory is an indispensable device for classical information technology. Analog to this, for quantum information technology, it is desirable to have a Random Access quantum memory with many memory cells and programmable Access to each cell. We report an experiment that realizes a Random Access quantum memory of 105 qubits carried by 210 memory cells in a macroscopic atomic ensemble. We demonstrate storage of optical qubits into these memory cells and their read out at programmable times by arbitrary orders with fidelities exceeding any classical bound. Experimental realization of a Random Access quantum memory with many memory cells and programmable control of its write-in and read out makes an important step for its application in quantum communication, networking, and computation
