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ACM Trans. Embedded Comput. Syst. 01/2007; 6.
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ACM Trans. Embedded Comput. Syst. 01/2006; 5:321-341.
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2006 IEEE International Conference on Application-Specific Systems, Architecture and Processors (ASAP 2006), 11-13 September 2006, Steamboat Springs, Colorado, USA; 01/2006
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ABSTRACT: Recently, a static power management with parallelism (P-SPM) technique has been proposed to reduce the energy consumption of distributed systems to execute a set of real-time dependent tasks (Mishra et al., 2003). The authors claimed that the proposed P-SPM outperforms other known methods in energy reduction. However, how to take advantage of the local static slack for further energy optimization remains as an open problem. In this paper, we propose the static power management with proportional distribution and parallelism scheme (PDP-SPM) that not only answers this open problem, but also exploits the parallelism. Simulations on task graphs derived for DSP applications and TGFF benchmark suite suggest that PDP-SPM achieves 64% energy saving over the system without power management, and 15% over the P-SPM scheme.
Design Automation Conference, 2005. Proceedings of the ASP-DAC 2005. Asia and South Pacific; 02/2005
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ABSTRACT: Multimedia applications have intrinsic quality of service (QoS) requirements that may not be captured by the simple traditional completion ratio model. We have proposed a new quantitative QoS metric based on the task completion ratio while differentiating firm and soft deadlines and taking data dependency into consideration. Using the decoding of MPEG movies as an example, we have shown that the proposed QoS metric is much better than the completion ratio in measuring the quality of presentation (QoP) of the movies. Based on the new QoS metric, we present a set of new online algorithms that outperform popular scheduling algorithms (such as EDF, FCFS, and LETF) and enhance QoP significantly, particularly when the system is overloaded. All the proposed online algorithms have low computation overhead and can be easily integrated into real-time operating systems to improve a multimedia embedded system's performance and/or to save system resources.
Circuits and Systems, 2004. ISCAS '04. Proceedings of the 2004 International Symposium on; 06/2004
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ABSTRACT: Location discovery in wireless sensor network (WSN) is the process that sensor nodes collaborate to determine the position for unknown sensor nodes. Anchors, sensors that know their locations, are expensive but are required to be deployed into the WSN to solve this problem. Thus it is desirable to minimize the number of anchors for this purpose. In this paper, we propose an anchor deployment scheme and a novel bilateration locationing algorithm to achieve this goal. The basic idea of anchor deployment method is to have three anchors deployed as a group, and locate sensors around them expansively. The novelty of our bilateration algorithm is that it in general requires only two neighbor sensors to determine a node's location. Comparing with the state-of-the-art location discovery approaches, our algorithm gives location estimation with high accuracy, low communication cost and very small anchor percentage. We conduct theoretical analysis about location estimation error and extensive simulation shows that our algorithm can derive sensor location within 4% location error and much less communication cost compared with other algorithms.
01/2004;
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Proceedings of the 2004 International Conference on Compilers, Architecture, and Synthesis for Embedded Systems, CASES 2004, Washington DC, USA, September 22 - 25, 2004; 01/2004
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ABSTRACT: Dynamic voltage scaling (DVS) is arguably the most effective energy reduction technique. The multiple-voltage DVS systems, which can operate only at pre-determined discrete voltages, are practical and have been well studied. However, one important unsolved problem is how many levels and at which values should voltages be implemented on a multiple-voltage DVS system to achieve the maximum energy saving. We refer this as the voltage set-up problem. In this paper, (1) we derive analytical solutions for dual-voltage system. (2) For the general case that does not have analytic solutions, we develop efficient numerical methods. (3) We demonstrate how to apply the proposed algorithms on system design. (4) Interestingly, the experimental results suggest that the multiple-voltage DVS system, when the voltages are set up properly, can reach DVS technique's full potential in energy saving. Specifically, on the design of an ad hoc application-specific system and the design of the MPEG video encoder, we find that the best single-voltage systems consume 150% and 20% more energy than the tight theoretical lower bounds, respectively. However, our approach gives dual-, 3-, and 4-voltage DVS system settings that are only 17.6%, 4.9%, and 2.6% for the ad hoc system, and 4.0%, 1.1%, and 0.2% for the MPEG video encoder, over the same lower bounds.
Computer Aided Design, 2003. ICCAD-2003. International Conference on; 12/2003
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ABSTRACT: MPEG video decoding algorithm has been embedded into many consumer electronic products. In this paper, we demonstrate that the completion ratio (CR) does not represent well the quality of presentation (QoP) of MPEG video. We then propose a new QoP metric, which 1) is based on frame completion ratio but 2) differentiates firm and soft deadlines and also 3) considers the frame dependency. We show that, on a set of simulates MPEG movies; the proposed QoP metric measures the QoP of the movies much better than completion ratio. We then present a set of online scheduling algorithms that enhance QoP significantly, particularly for overloaded systems.
IEEE Transactions on Consumer Electronics 12/2003; · 0.94 Impact Factor
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ABSTRACT: This paper develops energy-driven completion ratio guaranteed scheduling techniques for the implementation of embedded software on multi-processor system with multiple supply voltages. We leverage application's performance requirements, uncertainties in execution time, and tolerance for reasonable execution failures to scale processors' supply voltages at run-time to reduce energy consumption. Specifically, we study how to trade the di#erence between the highest achievable completion and the required completion ratio for energy saving.
09/2003;
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ABSTRACT: Many embedded systems such as PDAs require processing of the given applications with rigid power budget. However, they are able to tolerate occasional failures due to the imperfect human visual/auditory systems. The problem we address in this paper is how to utilize such tolerance to reduce multimedia system's energy consumption for providing guaranteed quality of service at the user level in terms of completion ratio. We explore a range of o#ine and on-line strategies that take this tolerance into account in conjunction with the modest non-determinism in application's execution time. First, we give a simple best-e#ort approach that achieves the maximum completion ratio; then we propose an enhanced on-line best-e#ort energy minimization (BEEM) approach and a hybrid o#ine/on-line minimume #ort (O ME) approach. We prove that BEEM maintains the maximum completion ratio while consuming the provably least amount of energy and O ME guarantees the required completion ratio statistically. We apply both approaches to a variety of benchmark task graphs, most from popular DSP applications. Simulation results show that significant energy savings (38% for BEEM and 54% for O ME, both over the simple best-e#ort approach) can be achieved while meeting the required completion ratio requirements.
08/2003;
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ABSTRACT: Dropped or incorrectly decoded frames degrade a video's quality of presentation (QoP), which can be conveniently measured by the number of correctly decoded frames. We demonstrate that the frame completion ratio (CR) does not represent well the QoP of an MPEG video. We then propose a new QoP metric and a set of online scheduling algorithms that achieve better QoP, particularly for overloaded systems.
Consumer Electronics, 2003. ICCE. 2003 IEEE International Conference on; 07/2003
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ABSTRACT: In this paper, we propose the novel concept of probabilistic design for multimedia systems and a methodology to quickly explore such design space at an early design stage. The probabilistic design is motivated by the challenge of how to design, but not over-design, multimedia embedded systems while systematically incorporating such application's performance requirements, uncertainties in execution time, and tolerance for reasonable execution failures. Our goal is to bridge the gap between real-time analysis and embedded software implementation for rapid and economic (multimedia) system prototyping. Our method takes advantage of multimedia system's unique features mentioned above to relax the rigid hardware requirements for software implementation and eventually avoid over-designing the system.
Rapid Systems Prototyping, 2003. Proceedings. 14th IEEE International Workshop on; 07/2003
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ABSTRACT: Many embedded systems such as PDAs require processing of the given applications with rigid power budget. However, they are able to tolerate occasional failures due to the imperfect human visual/auditory systems. The problem we address in this paper is how to utilize such tolerance to reduce multimedia system's energy consumption for providing guaranteed quality of service at the user level in terms of completion ratio. We explore a range of offline and on-line strategies that take this tolerance into account in conjunction with the modest non-determinism in application's execution time. First, we give a simple best-effort approach that achieves the maximum completion ratio; then we propose an enhanced on-line best-effort energy minimization (BEEM) approach and a hybrid offline/on-line minimum effort (O<sup>2</sup> ME) approach. We prove that BEEM maintains the maximum completion ratio while consuming the probably least amount of energy and O<sup>2</sup> ME guarantees the required completion ratio statistically. We apply both approaches to a variety of benchmark task graphs, most from popular DSP applications. Simulation results show that significant energy savings (38% for BEEM and 54% for O<sup>2</sup> ME, both over the simple best-effort approach) can be achieved while meeting the required completion ratio requirements.
Design Automation Conference, 2003. Proceedings; 07/2003
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ABSTRACT: Real-time applications often have mixed hard and soft deadlines, can be preempted subject to the cost of context switching or the restart of computation, and have various data dependency. The simple but widely used task completion ratio, as the quality of service (QoS) metric, does not capture these characteristics and can not reflect user perceived QoS well. In this paper, we propose a new quantitative QoS metric, which is based on task completion ratio but differentiates hard and soft deadlines and models data dependency as well. Basically, it assigns different weights to hard and soft deadline tasks, penalizes late soft task completion, and measures the tasks affected by any dropped tasks. We apply popular online schedulers such as EDF (earliest deadline first), FCFS (first come first serve), and LETF (least execution time first), on a set of simulated MPEG movies at the-frame level and for each application compare the new QoS measurement, traditional completion ratio with the "real" completion ratio which considers the number of correctly decoded frames and has been mapped to the user perceived QoS well. Experimental results show that our proposed QoS metric can reflect real life QoS much better than the traditional one.
Information Technology: Coding and Computing [Computers and Communications], 2003. Proceedings. ITCC 2003. International Conference on; 05/2003
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ABSTRACT: In this paper, we propose the novel concept of probabilistic design for multimedia systems and a methodology to quickly explore such design space at an early design stage. The probabilistic design is motivated by the challenge of how to design, but not over-design, multimedia embedded systems while systematically incorporating such application 's performance requirements, uncertainties in execution time, and tolerance for reasonable execution failures. Our goal is to bridge the gap between real-time analysis and embedded software implementation for rapid and economic (multimedia) system prototyping. Our method takes advantage of multimedia system's unique features mentioned above to relax the rigid hardware requirements for software implementation and eventually avoid over-designing the system.
05/2003;
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First Workshop on Embedded Systems for Real-Time Multimedia, ESTImedia 2003, October 3-4, 2003, Newport Beach, California, USA, co-located with CODES-ISSS 2003, Proceedings; 01/2003
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Embedded Software, Third International Conference, EMSOFT 2003, Philadelphia, PA, USA, October 13-15, 2003, Proceedings; 01/2003
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Proceedings of the 40th Design Automation Conference, DAC 2003, Anaheim, CA, USA, June 2-6, 2003; 01/2003
