Yung-Feng Lu

A driver-layer caching policy for removable storage devices

The growing popularity of flash memory is expected to draw attention to the limitations of file-system performance over flash memory. This work was motivated by the modular designs of operating system components such as bus and device drivers. A filter-driver-layered caching design is proposed to resolve the performance gap among file systems and to improve their performance with the considerations of flash memory characteristics. An efficient hybrid tree structure is presented to organize and manipulate the intervals of cached writes. Algorithms are proposed in the merging, padding, and removing of the data of writes. The effectiveness of the proposed approach is demonstrated with some analysis study of FAT-formatted and NTFS-formatted USB flash disks. The proposed cohesive caching policy was implemented as a filter driver in Windows XP/Vista for performance evaluation. In the experiments, a ten-fold or larger performance improvement was usually achieved when the cache size was only 64KB. Other substantial improvements were also observed in the experiments. For example, the proposed design enabled FAT-formatted and NTFS-formatted flash-memory devices to copy Linux image files 93% and 14% faster than conventional flash drives, respectively.

Design and implementation of SIP security

Session Initiation Protocol (SIP) is the Internet Engineering Task Force (IETF) standard for IP telephony. It is the most promising candidate as a signaling protocol for the future IP telephony services. Comparing with the reliability provided by the traditional telephone systems, there is an obvious need to provide a certain level of quality and security for IP telephony. The problem of security is tightly related to the signaling mechanisms and the service provisioning model. Therefore, there is a very hot topic in the SIP and IP telephony standardization for security support. In this paper, we propose a security mechanism for SIP-based voice over IP (VoIP) systems. Specifically, we focus on the design and implementation of SIP authentication for VoIP users. The performance issues for our secure SIP-based VoIP systems are also investigated. By means of a real testbed implementation, we provide an experimental performance analysis of our SIP security mechanisms, and compare the performance with the methods described in standardization.

A novel key management scheme for wireless embedded systems

Wireless Embedded Systems (WEBs) has attracted significant interest in recent years, for instance, Wireless Sensor Networks (WSN), have recently been in the limelight for many domains. The characteristics of WEBs have imposed various restrictions on their system designs. Since embedded systems usually are developed by low-cost hardware, one major challenge in the development of many WEBs applications is to provide high-security features with limited resources. In this paper, we propose a novel key establishment scheme, named half-key scheme that based on the well-known random key pre-distribution scheme and DDHV-D deployment knowledge to provide resource-efficient key management in WEBs with reduced memory space requirements and better security enforcement. The capability of the proposed approach is evaluated by an analytical model and a series of experiments.

EMWF for Flexible Automation and Assistive Devices

This paper describes an embedded workflow framework (EMWF) that enables flexible personal and home automation and assistive devices and service and social robots (collectively referred to as SISARL) to be built on workflow architecture The process definition language supported by EMWF is called SISARL-XPDL. It consists of a subset of the WfMC standard XML Process Definition Language (XPDL) 2.0, together with elements that implement common mechanisms for robot behavior coordination. SISARL-XPDL definitions of workflows are first translated into standard XPDL and execution directives and then are parsed either directly into binary workflow scripts for execution or into intermediate scripts in C. EMWF provides workflow engines for Linux and Windows CE platforms. The engines are written in C in order to keep their memory footprint and runtime overhead small. Performance data show that the overheads introduced by the engine and workflow data are tolerable for most SISARL devices.

Robust and flexible tunnel management for secure private cloud

Private cloud is cloud infrastructure operated solely for a single organization, whether managed internally or by a third-party and hosted internally or externally. It provides a flexible way to extend the working environment. Since the business process that working on them could be critical, it is important to provide a secure environment for organizations to execute those processes. While user mobility has become an important feature for many systems, technologies that provide users a lower cost and flexible way in joining a secure private cloud are in a strong demand. This paper exploits the key management mechanisms to have secured tunnels with private cloud for users who might move around dynamically without carrying the same machine. A strong authentication with a key agreement scheme is proposed to establish the secure tunnel. Furthermore, the proposed framework also provides mutual authentication, session key renewal between the users and the cloud server. Several related security properties of the proposed mechanism are also presented.

Scheduling algorithm with energy-response trade-off considerations for mixed task sets

This paper aims to investigate the scheduling problem of a mixed task set consisting of periodic tasks and aperiodic jobs in a real-time system. When a mixed task set is executed, a scheduling algorithm has to consider not only the system energy consumption but also the response time of the aperiodic jobs which do not want to be prolonged seriously. This paper proposes the Ratio Reclaim Algorithm (RRA) that reclaims the unused execution time for periodic jobs based on a user-defined ratio. For the convenience of maintaining effectively unused execution time left by early completed jobs, the earliness-queue is presented to reduce the memory space that the earliness-queue occupies. A series of experiments are conducted to evaluate the proposed algorithm. The experimental results demonstrate that the RRA scheme with a suitable user-defined value has a better performance than the compared scheme.

Task assignment with energy efficiency considerations for non-DVS heterogeneous multiprocessor systems

Currently, the multiprocessor architecture platform becomes more and more popular to the applications with higher computational capacity for meeting the fast-grown demand of applications and increasing the performance of whole system. Managing the consumption of resources has become an important issue in many different settings. The energyefficient scheduling for multiprocessors becomes one of important research issues. In this paper we study the scheduling problem of a heterogeneous non-DVSmultiprocessor platform with a task set. The processors have different characteristics of power consumption. We propose an off-line taskto- processor assignment algorithm, the Best-Fit Decreasing Physical Power Consumption (BDPC) algorithm to derive a feasible task assignment with the minimal energy consumption and has the time complexity of O(N(logN + M)), where N and M are the numbers of tasks and processor types, respectively. A series of experiments were conducted to evaluate the proposed algorithm. The experimental results demonstrate that the performance of the proposed BDPC algorithm is better than the compared algorithms.

A path generation scheme for real-time green internet of things

Internet of Things (IoT) is expected to offer promising solutions to transform the operation and role of many existing systems such as transportation systems, manufacturing systems, and enables many applications in many domains. IoT aims to connect different things over the network. The goal of IoT is to provide a good and efficient service for many applications. A real-time IoT applications must react to stimuli from its environment within time intervals dictated by its environment. The instant when a result must be produced is called a deadline. Wireless Sensor Networks (WSN) have recently used been in the limelight for many domains. The IoT can be explained as a general purpose sensor network. WSNs will constitute an integral part of the IoT paradigm, spanning many different application areas. Since sensor nodes usually are developed by low-cost hardware, one major challenge in the development of many sensor-network applications is to provide high-security features with limited resources. In this paper, we propose a path generation framework with deadline considerations for real-time query processing. To meet the deadline, the framework will assign the time budget to the routing path, and then, derive a feasible path with the assigned time budget. In order to evaluate the performance of the proposed RTQP scheme, we construct a simulation model using ns 2.35. The performance of the RTQP scheme is compared with that of other related mechanisms, for which we have very encouraging results.

A strong authentication with key agreement scheme for web-based collaborative systems

This paper presents a two-factor authentication with key agreement scheme for web-based collaborative systems. The proposed mechanism integrates URI fragment identifier with secure email token and identity-based remote mutual authentication scheme on ECC. It supports flawless two-factor and mutual authentication of participants and agreement of session key. The proposed mechanism does not require modifying the software of clients; thus, it is highly flexibly. We believe the proposed mechanism is usable for web-based applications.

A half-key key management scheme for wireless sensor networks

Wireless Sensor Networks (WSN) have recently been in the limelight for many domains. The characteristics of sensor networks have imposed various restrictions on their system designs. Since sensor nodes usually are developed by low-cost hardware, one major challenge in the development of many sensor-network applications is to provide high-security features with limited resources. In this paper, we propose a half-key scheme based on the well-known random key pre-distribution scheme and DDHV-D deployment knowledge to provide resource-efficient key management in wireless sensor networks with reduced memory space requirements and better security enforcement. The capability of the proposed approach is evaluated by an analytical model and a series of experiments.