We present our initial findings in the investigation of an adaptive protocol for relaying of information in tactical packet-radio networks. Our protocol employs fountain codes to facilitate a relaying scheme involving...
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ISBN:
(纸本)9781479967704
We present our initial findings in the investigation of an adaptive protocol for relaying of information in tactical packet-radio networks. Our protocol employs fountain codes to facilitate a relaying scheme involving two relays for improved throughput. In addition, the protocol adapts the modulation format and error-control code for each packet transmission in response to the time-varying propagation loss in the channel. The adaptation is carried out with the help of simple statistics that can be easily derived from the decoder.
We study leakage-power reduction in standby random access memories (SRAMs) during data-retention. An SRAM cell requires a minimum critical supply voltage (DRV) above which it preserves the stored-bit reliably. Due to ...
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ISBN:
(纸本)9781424409204
We study leakage-power reduction in standby random access memories (SRAMs) during data-retention. An SRAM cell requires a minimum critical supply voltage (DRV) above which it preserves the stored-bit reliably. Due to process-variations, the intra-chip DRV exhibits variation with a distribution having a diminishing tail. In order to minimize leakage power while preserving data reliably, existing low-power design methods use a worst-case standby supply voltage. This worst-case voltage is larger than the highest DRV among all cells in an SRAM. In contrast, our approach uses aggressive voltage reduction and counters the ensuing unreliability by an error-control code based memory architecture. Using this approach, we explore fundamental trade-offs between power reduction and redundancy present in the SRAM. We establish fundamental bounds on the power reduction in terms of the DRV-distribution using techniques from information theory and algebraic coding theory. For an experimental test-chip DRV-distribution in the 90nm CMOS technology, we show that 49% power reduction with respect to (w.r.t.) the worst-case is a fundamental lower bound while 40% power reduction w.r.t. the worst-case is achievable by using a practical algebraic coding scheme. We also study the power reduction as a function of the block-length for low-latency codes since most applications using SRAM are latency constrained. We propose a reliable low-power memory architecture based on the Hamming code for the next test-chip implementation with a predicted power reduction of 33% while accounting for coding overheads.
Phase-change memory (PCM) is an emerging nonvolatile memory technology that promises very high performance. It currently uses discrete cell levels to represent data, controlled by a single amorphous/crystalline domain...
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ISBN:
(纸本)9781457705953
Phase-change memory (PCM) is an emerging nonvolatile memory technology that promises very high performance. It currently uses discrete cell levels to represent data, controlled by a single amorphous/crystalline domain in a cell. To improve data density, more levels per cell are needed. There exist a number of challenges, including cell programming noise, drifting of cell levels, and the high power requirement for cell programming. In this paper, we present a new cell structure called patterned cell, and explore its data representation schemes. Multiple domains per cell are used, and their connectivity is used to store data. We analyze its storage capacity, and study its error-correction capability and the construction of error-control codes.
The most efficient transmission system of the transport network is OTN offered by ITU-T G. 709. However, in this recommendation, there is no indication as to what degree of MQAM determining the number of points of sig...
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ISBN:
(纸本)9781538610565
The most efficient transmission system of the transport network is OTN offered by ITU-T G. 709. However, in this recommendation, there is no indication as to what degree of MQAM determining the number of points of signal constellation provides the maximum capacity of multichannel system. This work removes this gap.
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