17429132
Rule-base technique for component adaptation to support QoS-based reconfiguration
Many critical application systems require reconfigurability in order to adapt under changing environment. To achieve system reconfigurability, it is possible to use adaptation mechanisms that are external to components or to use parameterized components. This paper focuses on making components reconfigurable in terms of QoS tradeoffs. We propose a new component parameterization technique which can transform individual components to reconfigurable ones such that they can support various QoS tradeoffs to achieve overall system QoS requirements. The parameterized components can be used to develop both statically and dynamically reconfigurable systems. The proposed technique is rule based, which provides flexibility and extensibility to enhance and improve the technique. A tool set has been developed based on the proposed technique to achieve semi-automated component parameterization.
1003875
A software enhancement system for embedded software development
This paper proposes a rule-based expert system model to assist developers in enhancing the quality of embedded software. The expert system supports semi-automated source code enhancements from multiple perspectives including optimization, reconfiguration to achieve quality of service (QoS) trade-offs, conformance to coding standards, etc., by defining a rule base that is composed of modularized and extensible rule sets. The rule sets are composed of re-usable rules; the rules capture the in-depth knowledge of different software experts. The expert system also adopts a technique to support automated fact generation. This allows the expert system to support processing programs developed in different programming languages
14293786
QoS analysis for component-based embedded software: Model and methodology
Component-based development (CBD) techniques have been widely used to enhance the productivity and reduce the cost for software systems development. However, applying CBD techniques to embedded software development faces additional challenges. For embedded systems, it is crucial to consider the quality of service (QoS) attributes, such as timeliness, memory limitations, output precision, and battery constraints. Frequently, multiple components implementing the same functionality with different QoS properties (measurements in terms of QoS attributes) can be used to compose a system. Also, software components may have parameters that can be configured to satisfy different QoS requirements. Composition analysis, which is used to determine the most suitable component selections and parameter settings to best satisfy the system QoS requirement, is very important in embedded software development process. In this paper, we present a model and the methodologies to facilitate composition analysis. We define QoS requirements as constraints and objectives. Composition analysis is performed based on the QoS properties and requirements to find solutions (component selections and parameter settings) that can optimize the QoS objectives while satisfying the QoS constraints. We use a multi-objective concept to model the composition analysis problem and use an evolutionary algorithm to determine the Pareto-optimal solutions efficiently.
15203011
Code Parameterization for Satisfaction of QoS Requirements in Embedded Software
The rapid growth of embedded systems urgently requires methods of improving the development process for these systems. Component-based development (CBD) techniques have been widely studied to enhance the productivity of developing complex applications. These techniques can benefit the software development process for embedded systems as well as other application domains. However, applying CBD techniques to embedded software development faces additional challenges. For embedded systems, it is crucial to consider the QoS attributes, such as timeliness, memory limitations, output precision, battery constraints, etc. However, it is often difficult to adjust the QoS properties of a system integrated from components that do not consider QoS properties in the first place. In this paper, we present an overview of a repository-based embedded software development methodology and then focus on component parameterization techniques. The basic concept of the parameterization process is to identify configurable parameters in a component that can be parameterized to achieve QoS tradeoffs. The component is then modified to a reconfigurable one such that its configurable parameters can be adjusted to satisfy different QoS requirements for various applications or for dynamical changing execution environment. A rule base is used to assist the parameter identification process. We also develop delta file technique to facilitate component adaptation and testing tools for QoS data collection. Keywords-embedded system, component parameterization, QoS, Repository system
2326563
Improving Database Performance on Simultaneous Multithreading Processors
Simultaneous multithreading (SMT) allows multiple threads to supply instructions to the instruction pipeline of a superscalar processor. Because threads share processor resources, an SMT system is inherently different from a multiprocessor system and, therefore, utilizing multiple threads on an SMT processor creates new challenges for database implementers.We investigate three thread-based techniques to exploit SMT architectures on memory-resident data. First, we consider running independent operations in separate threads, a technique applied to conventional multi-processor systems. Second, we describe a novel implementation strategy in which individual operators are implemented in a multi-threaded fashion. Finally, we introduce a new data-structure called a work-ahead set that allows us to use one of the threads to aggressively preload data into the cache.We evaluate each method with respect to its performance, implementation complexity, and other measures. We also provide guidance regarding when and how to best utilize the various threading techniques. Our experimental results show that by taking advantage of SMT technology we achieve a 30% to 70% improvement in throughput over single threaded implementations on in-memory database operations.
37696445
Cryptanalysis of a Wavelet Based Watermarking Scheme
In this paper we cryptanalyze the wavelet based watermarking scheme by Wang et al, 2002. By cryptanalysis we mean the removal of the watermark using a single watermarked copy which is equivalent to cipher text only jamming attack. The watermark embedding process replaces a particular middle frequency band of the host image (in wavelet domain) with the watermark. In the scheme, the key consists of three secrets: (i) the watermark, (ii) the random filter bank used for wavelet transform and (iii) the wavelet band where the watermark is inserted. First we observe that the secret random filter bank does not provide any security since it can be replaced by any filter bank from a large class. Further, it is possible to discover the secret wavelet band used to watermark the host image. Though in cryptography the random nature of secret key provides the security, in contrary here we show that the random nature of the watermark actually helps in identifying the secret wavelet band and consequently one can remove the watermarking signal from that band to mount the successful cryptanalytic attack.
9836982
Undeniable Mobile Billing Schemes
An undeniable mobile billing system allows a mobile network service provider to bill its subscribers with trustworthy evidences. Chen, Jan and Chen proposed such a billing system by introducing a trusted third party - Observer and exploiting a hash chain mechanism. In their system, the Observer provides call time evidence to both cellular carriers and subscribers for billing. In this paper, we first identify some vulnerabilities in their mobile billing system. Then, we propose an undeniable billing scheme based on a proper combination of digital signature and hash chain mechanism. The proposed scheme can achieve authentication, non-repudiation, and fairness, which are desirable security requirements for an undeniable mobile billing system.
15695658
Performance Evaluation of Directional Adaptive Range Control in Mobile Ad Hoc Networks
This paper presents DARC (Directional Adaptive Range Control), a range control mechanism using directional antennas to be implemented across multiple layers. DARC uses directional reception for range control rather than directional transmission in order to achieve both range extension and high spatial reuse. It adaptively controls the communication range by estimating dynamically changing local network density based on the transmission activities around each network node. The experimental results using simulation with detailed physical layer, IEEE 802.11 DCF MAC, and AODV protocol models have shown the successful adaptation of communication range with DARC for varied network densities and traffic loads. DARC improves the packet delivery ratio by a factor of 9 at the maximum for sparse networks while it maintains the increased network capacity for dense networks. Further, as each node adaptively changes the communication range, the network delivers up to 20% more packets with DARC compared to any fixed range configurations.
34424162
Minimizing TTP's involvement in signature validation
A digital signature applied on a message could serve as irrefutable cryptographic evidence to prove its origin and integrity. However, evidence solely based on digital signatures may not enforce strong non-repudiation. Additional mechanisms are needed to make digital signatures as valid non-repudiation evidence in the settlement of possible disputes. Most of existing mechanisms for maintaining the validity of digital signatures rely on the supporting services from trusted third parties, e.g., time-stamping and certificate revocation. Obviously, this is less efficient for on-line transactions. In this paper, we propose two new schemes for validating digital signatures as non-repudiation evidence that minimize the trusted third party's involvement.