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3rd Conference on Hypercube Concurrent computers and Applications, C3P 1988

作者： Kandlur, Dilip D. Shin, Kang G. Real-time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109-2122 United States

ISBN: (纸本)0897912780

The problem of allocation and release of subcubes from a hypercube with node failures is addressed. Two algorithms are presented, both based on the Buddy allocation scheme for memory management which is also used by the AXIS operating system of the NCUBE hypercube computer. The first algorithm is a simple variation of the Buddy algorithm which permits the efficient allocation of subcubes in the presence of a single faulty node. The second algorithm, which effectively subsumes the first, tries to reduce the fragmentation caused by multiple failed nodes. It uses a relabeling scheme to group the failed nodes so that large non-faulty subcubes can be detected using the Buddy allocation scheme. The relative performance of these algorithms is studied using simulation and the proposed algorithms are shown to have a consistently better performance. Issues relating to the detection of faulty nodes on the NCUBE computer and the consequences of the relabeling on message passing are also discussed. © ACM 1988.

关键词： Message passing

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Evaluation of load sharing in HARTS while considering message routing and broadcasting 93

Evaluation of load sharing in HARTS while considering messag...

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1993 ACM SIGMETRICS Conference on Measurement and Modeling of computer Systems, SIGMETRICS 1993

作者： Shin, Kang G. Hou, Chao-Ju Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109-2122 United States

In this paper, we apply the load sharing (LS) mechanism proposed in [1, 2] to HARTS, an experimental distributed realtime system [3] currently being built at the real-time computing laboratory of the University of Mic... 详细信息

ISBN: (纸本)0897915801

关键词： Distributed computer systems

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Embedding triple-modular redundancy into a hypercube architecture 3

Embedding triple-modular redundancy into a hypercube archite...

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3rd Conference on Hypercube Concurrent computers and Applications, C3P 1988

作者： Kiskis, Daniel L. Shin, Kang G. Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109-2122 United States

ISBN: (纸本)0897912780

This paper describes an embedding of Triple Modular Redundancy (TMR) into a binary hypercube. The goal is to improve fault tolerance by masking any single-point faults. Each module of an application task is triplicated and executed in parallel on three nodes of a 2-dimensional subcube (Q2) of the hypercube. Each of these nodes also executes a voter process. The remaining node is used for message passing only. All outputs from the triplicated modules are voted on, and the voting results are transmitted to the appropriate destination. Thus, all interunit messages are also triplicated. We propose an embedding of TMR into a hypercube which can be implemented in a manner transparent to the application program. Subcubes are allocated so that the address space for the TMR units is also a hypercube. Hence, the subcube allocation and intermodule communication schemes are defined to be analogous to the schemes used in the nonre-dundant system. The embedded system is proven to mask all single-point faults.

关键词： Message passing

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QoS-Sensitive protocol processing in shared-memory multiprocessor multimedia servers 3

QoS-Sensitive protocol processing in shared-memory multiproc...

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3rd IEEE Workshop on the Architecture and Implementation of High Performance Communication Subsystems, HPCS 1995

作者： Mehra, A. Shin, Kang G. Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109-2122 United States

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Pre-Chirp-Domain Index Modulation for Full-Diversity Affine Frequency Division Multiplexing towards 6G

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IEEE Transactions on Wireless Communications 2025年

作者： Liu, Guangyao Mao, Tianqi Xiao, Zhenyu Wen, Miaowen Liu, Ruiqi Zhao, Jingjing Basar, Ertugrul Wang, Zhaocheng Chen, Sheng Beihang University School of Electronic and Information Engineering State Key Laboratory of CNS/ATM Beijing100191 China Greater Bay Area Innovation Research Institute of BIT Zhuhai519000 China Zhuhai519088 China South China University of Technology School of Electronic and Information Engineering Guangzhou510640 China ZTE Corporation Wireless and Computing Research Institute Beijing100029 China State Key Laboratory of Mobile Network and Mobile Multimedia Technology Shenzhen518055 China Tampere University Department of Electrical Engineering Tampere33720 Finland Koc University Department of Electrical and Electronics Engineering Sariyer Istanbul34450 Turkey Tsinghua University Department of Electronic Engineering Beijing100084 China University of Southampton School of Electronics and Computer Science SouthamptonSO17 1BJ United Kingdom

As a superior multicarrier technique utilizing chirp signals for high-mobility communications, affine frequency division multiplexing (AFDM) is envisioned to be a promising candidate for sixth-generation (6G) wireless networks. AFDM is based on the discrete affine Fourier transform (DAFT) with two adjustable parameters of the chirp signals, termed the pre-chirp and post-chirp parameters, respectively. Whilst the post-chirp parameter complies with stringent constraints to combat the time-frequency doubly selective channel fading, we show that the pre-chirp counterpart can be flexibly manipulated for an additional degree of freedom. Therefore, this paper proposes a novel AFDM scheme with the pre-chirp index modulation (PIM) philosophy (AFDM-PIM), which can implicitly convey extra information bits through dynamic pre-chirp parameter assignment, thus enhancing both spectral and energy efficiency. Specifically, we first demonstrate that the subcarrier orthogonality is still maintained by applying distinct pre-chirp parameters to various subcarriers in the AFDM modulation process. Inspired by this property, we allow each AFDM subcarrier to carry a unique pre-chirp signal according to the incoming bits. By such an arrangement, extra bits can be embedded into the index patterns of pre-chirp parameter assignment without additional energy consumption. We derive asymptotically tight upper bounds on the average bit error probability (BEP) of the proposed schemes with the maximum-likelihood detection, and validate that the proposed AFDM-PIM can achieve full diversity under doubly dispersive channels. Based on the derived result, we further propose an optimal pre-chirp alphabet design to enhance the bit error rate (BER) performance via intelligent optimization algorithms. Simulation results demonstrate that the proposed AFDM-PIM outperforms the classical benchmarks. © 2002-2012 IEEE.

关键词： Chirp modulation

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A model-based approach to system-level dependency and real-time analysis of embedded software

A model-based approach to system-level dependency and real-t...

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9th IEEE real-time and Embedded Technology and Applications Symposium, RTAS 2003

作者： Gu, Zonghua Kodase, S. Wang, Shige Shin, K.G. Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109-2122 United States

We describe an end-to-end tool-chain for model-based design and analysis of component-based embedded real-time software. All aspects of an embedded real-time system are captured in domain-specific models, including software components and architecture, timing and resource constraints, processes and threads, execution platforms, etc. We focus on the AIRES tool, which performs various static analysis tasks based on the models, including system-level dependency analysis, execution rate assignment to component ports, real-time and schedulability analysis, and automated allocation of components to processors. By capturing all relevant information explicitly in the models at the design-level, and performing analysis that provide insight into nonfunctional aspects of the system, we can raise the level of abstraction for the designer, and facilitate rapid system prototyping. © 2003 IEEE.

关键词： Static analysis

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Impact of mobility on spectrum sensing in cognitive radio networks

Impact of mobility on spectrum sensing in cognitive radio ne...

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2009 ACM Workshop on Cognitive Radio Networks, CoRoNet'09, Co-located with the Mobile computing and Networking Conference, MobiCom'09

作者： Min, Alexander W. Shin, Kang G. Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109-2121 United States

ISBN: (纸本)9781605587387

In cognitive radio networks (CRNs), spectrum sensing is key to opportunistic spectrum access while preventing any unacceptable interference to primary users' communications. Although cognitive radios function as spectrum sensors and move around, most, if not all, of existing approaches assume stationary spectrum sensors, thus providing inaccurate sensing results. As part of our effort to solve/alleviate this problem, we consider the impact of sensor mobility on spectrum sensing performance in a joint optimization framework for sensor cooperation and sensing scheduling. We show that sensor mobility increases spatio-temporal diversity in received primary signal strengths, and thus, improves the sensing performance. This is intuitively plausible, but have not been tested previously. Based on this observation, we propose a sensing strategy that minimizes the sensing overhead by finding an optimal combination of the number of sensors to cooperate and the number of times spectrum sensing must be scheduled. This result provides a useful insight to understand the spectrum sensing and its coupling with sensor mobility. Copyright 2009 ACM.

关键词： Cognitive radio

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Experimental evaluation of failure-detection schemes in real-time communication networks 27

Experimental evaluation of failure-detection schemes in real...

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27th Annual International Symposium on Fault-Tolerant computing, FTCS 1997

作者： Han, Seungjae Shin, Kang G. Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109-2122 United States

ISBN: (纸本)0818678313

An effective failure-detection scheme is essential for reliable communication services. Most computer network rely on behavior-based detection schemes: each node uses heartbeats to detect the failure of its neighbor nodes, and the transport protocol (like TCP) achieves reliable communication by acknowledgment/retransmission. In this paper, we experimentally evaluate the effectiveness of such behavior-based detection schemes in real-time communication. Specifically, we measure and analyze the coverage and latency of two failure-detection schemes-neighbor detection and end-to-end detection-through fault-injection experiments. The experimental results have shown that a significant portion of failures can be detected very quickly by the neighbor detection scheme, while the end-to-end detection scheme uncovers the remaining failures with larger detection latencies. © 1997 IEEE.

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Optimal load sharing in distributed real-time systems 6

Optimal load sharing in distributed real-time systems

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6th Distributed Memory computing Conference, DMCC 1991

作者： Chang, Yi-Chieh Shin, Kang G. Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109-2122 United States

ISBN: (纸本)0818622903

In hard real-time systems, the problem of scheduling periodic tasks to meet their deadlines has been studied extensively, but scheduling aperiodic tasks has been addressed far less, due mainly to their uncertain arrivals. The main intent of this paper is to derive an approximate, closed-form solution for the decentralized, dynamic load sharing (LS) problem treated in our early paper [1], Based on the derived solutions, we show that the probability of missing task deadlines can be kept below any required level while minimizing the communication overhead resulting from task transfers and state-information collection. Specifically, "optimal" threshold patterns and buddy set sizes are derived for different system loads by minimizing the communication overhead subject to a constraint of keeping the probability of missing task deadlines below any given level. (One can also derive optimal solutions by minimizing the probability of missing deadlines while keeping the communication overhead below a specified level.). © 1991 IEEE.

关键词： Probability

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Fast discovery of spectrum opportunities in cognitive radio networks

Fast discovery of spectrum opportunities in cognitive radio ...

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2008 3rd IEEE Symposium on New Frontiers in Dynamic Spectrum Access Networks, DySPAN 2008

作者： Kim, Hyoil Shin, Kang G. Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109-2121 United States

ISBN: (纸本)9781424420179

We address the problem of rapidly discovering spectrum opportunities for seamless service provisioning for secondary users (SUs) in cognitive radio networks (CRNs). Specifically, we propose an efficient sensing-sequence that incurs a small opportunity-discovery delay by considering (1) the probability that a spectrum band (or a channel) may be available at the time of sensing, (2) the duration of sensing on a channel, and (3) the channel capacity. We derive the optimal sensing-sequence for channels with homogeneous capacities, and a suboptimal sequence for channels with heterogeneous capacities for which the problem of finding the optimal sensing-sequence is shown to be NP-hard. To support the proposed sensing-sequence, we also propose a channel-management strategy that optimally selects and updates the list of backup channels. A hybrid of maximum likelihood (ML) and Bayesian inference is also introduced for flexible estimation of ON/OFF channel-usage patterns and prediction of channel availability when sensing produces infrequent samples. The proposed schemes are evaluated via in-depth simulation. For the scenarios we considered, the proposed suboptimal sequence is shown to achieve close-to-optimal performance, reducing the opportunity-discovery delay by up to 47% over an existing probability-based sequence. The hybrid estimation strategy is also shown to outperform the ML-only strategy by reducing the overall opportunity-discovery delay by up to 34%. ©2008 IEEE.

关键词： Bayesian networks

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