Vol. 5, No. 4, Aug. 2009
Minyi Guo, Yanqin Yang, Gongwei Zhang, Feilong Tang, Yao Shen
Vol. 5, No. 4, pp. 167-174, Aug. 2009
Keywords: Bluetooth, Statternet Formation, Bluetooth Communication Protocol
Show / Hide AbstractNowadays, it has become common to equip a device with Bluetooth. As such devices become pervasive in the world; much work has been done on forming them into a network, however, almost all the Bluetooth Scatternet Formation Algorithms assume devices are homogeneous. Even the exceptional algorithms barely mentioned a little about the different characteristics of devices like computational abilities, traffic loads for special nodes like bridge nodes or super nodes, which are usually the bottleneck in the scatternet. In this paper, we treat the devices differently not only based on the hardware characteristics, but also considering other conditions like different classes, different groups and so on. We use a two-phase Scatternet Formation Algorithm here: in the first phase, construct scatternets for a specified kind of devices; in the second phase, connect these scatternets by using least other kinds of devices as bridge nodes. Finally, we give some applications to show the benefit of classification.
Young Choon Lee, Albert Y Zomaya
Vol. 5, No. 4, pp. 175-186, Aug. 2009
Keywords: Scheduling, Energy awareness, Green Computing, Dynamic Voltage and Frequency Scaling, Data Centers
Show / Hide AbstractPower consumed by modern computer systems, particularly servers in data centers has almost reached an unacceptable level. However, their energy consumption is often not justifiable when their utilization is considered; that is, they tend to consume more energy than needed for their computing related jobs. Task scheduling in distributed computing systems (DCSs) can play a crucial role in increasing utilization; this will lead to the reduction in energy consumption. In this paper, we address the problem of scheduling precedence-constrained parallel applications in DCSs, and present two energyconscious scheduling algorithms. Our scheduling algorithms adopt dynamic voltage and frequency scaling (DVFS) to minimize energy consumption. DVFS, as an efficient power management technology, has been increasingly integrated into many recent commodity processors. DVFS enables these processors to operate with different voltage supply levels at the expense of sacrificing clock frequencies. In the context of scheduling, this multiple voltage facility implies that there is a trade-off between the quality of schedules and energy consumption. Our algorithms effectively balance these two performance goals using a novel objective function and its variant, which take into account both goals; this claim is verified by the results obtained from our extensive comparative evaluation study.
Mooseop Kim, Youngsae Kim, Hyunsook Cho
Vol. 5, No. 4, pp. 187-196, Aug. 2009
Keywords: Trusted Computing, MTM, Cryptographic circuit, RSA, HASH, Mobile Computing
Show / Hide AbstractThis paper presents compact cryptographic hardware architecture suitable for the Mobile Trusted Module (MTM) that requires low-area and low-power characteristics. The built-in cryptographic engine in the MTM is one of the most important circuit blocks and contributes to the performance of the whole platform because it is used as the key primitive supporting digital signature, platform integrity and command authentication. Unlike personal computers, mobile platforms have very stringent limitations with respect to available power, physical circuit area, and cost. Therefore special architecture and design methods for a compact cryptographic hardware module are required. The proposed cryptographic hardware has a chip area of 38K gates for RSA and 12.4K gates for unified SHA-1 and SHA-256 respectively on a 0.25um CMOS process. The current consumption of the proposed cryptographic hardware consumes at most 3.96mA for RSA and 2.16mA for SHA computations under the 25MHz.
Reijo M Savola
Vol. 5, No. 4, pp. 197-206, Aug. 2009
Keywords: security metrics, Security Objectives, Taxonomy, Correctness, Effectiveness, Efficiency
Show / Hide AbstractWe introduce a novel high-level security metrics objective taxonomization model for softwareintensive systems. The model systematizes and organizes security metrics development activities. It focuses on the security level and security performance of technical systems while taking into account the alignment of metrics objectives with different business and other management goals. The model emphasizes the roles of security-enforcing mechanisms, the overall security quality of the system under investigation, and secure system lifecycle, project and business management. Security correctness, effectiveness and efficiency are seen as the fundamental measurement objectives, determining the directions for more detailed security metrics development. Integration of the proposed model with riskdriven security metrics development approaches is also discussed.
Poongup Lee, Jangkeun Jeong, Navrati Saxena, Jitae Shin
Vol. 5, No. 4, pp. 207-220, Aug. 2009
Keywords: femtocell, Physical Cell Identity (PCI), Access Control, Long Term Evolution (LTE)
Show / Hide AbstractTA large number of phone calls and data services will take place in indoor environments. In Long Term Evolution (LTE), femtocell, as a home base station for indoor coverage extension and wideband data service, has recently gained significant interests from operators and consumers. Since femtocell is frequently turned on and off by a personal owner, not by a network operator, one of the key issues is that femtocell should be identified autonomously without system information to support handover from macrocell to femtocell. In this paper, we propose a dynamic reservation scheme of Physical Cell Identities (PCI) for 3GPP LTE femtocell systems. There are several reserving types, and each type reserves a different number of PCIs for femtocell. The transition among the types depends on the deployed number of femtocells, or the number of PCI confusion events. Accordingly, flexible use of PCIs can decrease PCI confusion. This reduces searching time for femtocell, and it is helpful for the quick handover from macrocell to femtocell. Simulation results show that our proposed scheme reduces average delay for identifying detected cells, and increases network capacity within equal delay constraints.
Vol. 5, No. 4, pp. 221-228, Aug. 2009
Keywords: AMR, AMI, Fault Tolerance, ZigBee
Show / Hide AbstractDue to low cost, low-power, and scalability, ZigBee is considered an efficient wireless AMR infrastructure. However, these characteristics of ZigBee can make the devices more vulnerable to unexpected error environments. In this paper, a fault-tolerant wireless AMR network (FWAMR) is proposed, which is designed to improve the robustness of the conventional ZigBee-based AMR systems by coping well with dynamic error environments. The experimental results demonstrate that the FWAMR is considerably fault-tolerant compared with the conventional ZigBee-based AMR network.
Sun Ok Yang, SungSuk Kim
Vol. 5, No. 4, pp. 229-236, Aug. 2009
Keywords: Notification Message, Parent Selection Message, Spatial Query Process, Minimum Bounding Area
Show / Hide AbstractSensors are deployed to gather physical, environmental data in sensor networks. Depending on scenarios, it is often assumed that it is difficult for batteries to be recharged or exchanged in sensors. Thus, sensors should be able to process users¡¯ queries in an energy-efficient manner. This paper proposes a spatial query processing scheme- Minimum Bounding Area Based Scheme. This scheme has a purpose to decrease the number of outgoing messages during query processing. To do that, each sensor has to maintain some partial information locally about the locations of descendent nodes. In the initial setup phase, the routing path is established. Each child node delivers to its parent node the location information including itself and all of its descendent nodes. A parent node has to maintain several minimum bounding boxes per child node. This scheme can reduce unnecessary message propagations for query processing. Finally, the experimental results show the effectiveness of the proposed scheme.
A Geometrical Center based Two-way Search Heuristic Algorithm for Vehicle Routing Problem with Pickups and DeliveriesKwangcheol Shin
Vol. 5, No. 4, pp. 237-242, Aug. 2009
Keywords: Vehicle Routing Problem, Heuristic Algorithm, Initial Solution
Show / Hide AbstractThe classical vehicle routing problem (VRP) can be extended by including customers who want to send goods to the depot. This type of VRP is called the vehicle routing problem with pickups and deliveries (VRPPD). This study proposes a novel way to solve VRPPD by introducing a two-phase heuristic routing algorithm which consists of a clustering phase and uses the geometrical center of a cluster and route establishment phase by applying a two-way search of each route after applying the TSP algorithm on each route. Experimental results show that the suggested algorithm can generate better initial solutions for more computer-intensive meta-heuristics than other existing methods such as the giant-tour-based partitioning method or the insertion-based method.