MAP Detector for Flash Memory Without Accessing the Interfering Cells

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Abstract

As the density of cells in flash memories increases, inter-cell interference becomes an important performance limitation. In this paper, we propose a novel method to detect word-lines that are subject to interference from neighboring cells. A strong feature of our method is that it does not incur the latency cost of accessing the interfering cells. Specifically, we exploit the fact that adjacent cells have common interferers by modeling the system as an appropriate hidden Markov model. Then we use the sum-product (message-passing) algorithm to compute the marginal posterior probabilities of the stored bits and perform maximum a posteriori detection. Another advantage of the proposed detector is that its complexity scales linearly with the number of cells that are detected together. Simulation results show that exploiting the dependency between the outputs of victim cells provides significant performance improvement, especially when the system is interference-limited and the “diagonal” coupling between cells is high.
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As the density of cells in flash memories increases, inter-cell interference becomes an important performance limitation. In this paper, we propose a novel method to detect word-lines that are subject to interference from neighboring cells. A strong feature of our method is that it does not incur the latency cost of accessing the interfering cells. Specifically, we exploit the fact that adjacent cells have common interferers by modeling the system as an appropriate hidden Markov model. Then we use the sum-product (message-passing) algorithm to compute the marginal posterior probabilities of the stored bits and perform maximum a posteriori detection. Another advantage of the proposed detector is that its complexity scales linearly with the number of cells that are detected together. Simulation results show that exploiting the dependency between the outputs of victim cells provides significant performance improvement, especially when the system is interference-limited and the “diagonal” coupling between cells is high.
Original languageEnglish
JournalI E E E Transactions on Circuits and Systems. Part 2: Express Briefs
ISSN1549-7747
Publication statusSubmitted - 2019
Publication categoryResearch
Peer-reviewedYes

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