17496994
On finding optimal registrations in presence of overlapping registration areas
Personal Communication Services (PCS) standards such as IS-41 and GSM use a location management scheme which is based on registration areas (RA). Overlapping of registration areas has been proposed to reduce the overhead of location updates in such systems (4]. Overlapping RAs form regions in which a mobile has a choice in selecting which RA to register to. The choice of current RA has implication on the number of registrations a mobile may require in the future. In this paper we investigate the problem of finding the best (or optimal) registration for a user in a cellular PCS environment with overlapping Registration Areas (RAs). We study two versions of the problem: (i) the deterministic version, where the entire trajectory of the mobile is known a-priori, and (ii) the stochastic version, where the trajectory of the mobile is not known a-priori but the system has the knowledge of mobility pattern of the mobile. The mobility pattern is modeled as a stochastic random walk across regions. In the deterministic case the method presented computes an optimal solution to the registration problem. In the stochastic case we present a method which determines the registration which minimizes the expected number of registrations by looking ahead at the probable paths which may be traversed by the mobile in future. The paper also proposes a preemptive and a non-preemptive version of the stochastic method which incur different numbers of hard and soft registration operations.
12873659
TARA: Thermal-Aware Routing Algorithm for Implanted Sensor Networks
Implanted biological sensors are a special class of wireless sensor networks that are used in-vivo for various medical applications. One of the major challenges of continuous in-vivo sensing is the heat generated by the implanted sensors due to communication radiation and circuitry power consumption. This paper addresses the issues of routing in implanted sensor networks. We propose a thermal-aware routing protocol that routes the data away from high temperature areas (hot spots). With this protocol each node estimates temperature change of its neighbors and routes packets around the hot spot area by a withdraw strategy. The proposed protocol can achieve a better balance of temperature rise and only experience a modest increased delay compared with shortest hop, but thermal-awareness also indicates the capability of load balance, which leads to less packet loss in high load situations.
1274772
Supporting persistent social groups in ubiquitous computing environments using context-aware ephemeral group service
We analyze the role of the social group in a ubiquitous computing (Ubicomp) environment as a source of contextual information. A model is presented to address the social group member's perceptions of how devices in a ubicomp environment should aid them in collaboration. Based on the model a distributed context-aware group membership management scheme is developed. We then present a prototype implementation for a context-aware ephemeral group membership management scheme, along with a sample application, and experimental results that demonstrate the feasibility of our system.
3266186
e3D: an energy-efficient routing algorithm for wireless sensor networks
One of the limitations of wireless sensor nodes is their inherent limited energy resource. Besides maximizing the lifetime of the sensor node, it is preferable to distribute the energy dissipated throughout the wireless sensor network in order to minimize maintenance and maximize overall system performance. Any communication protocol that involves synchronization of peer nodes incurs some overhead for setting up the communication. We introduce a new algorithm, e3D (energy-efficient distributed dynamic diffusion routing algorithm), and compare it to two other algorithms, namely directed, and random clustering communication. We take into account the setup costs and analyze the energy-efficiency and the useful lifetime of the system. We compare the algorithms in terms of system lifetime, power dissipation distribution, cost of synchronization, and simplicity of the algorithm. Our simulation results show that e3D performs comparable to its optimal counterpart while having significantly less overhead.
2580676
Adaptive Distributed Dynamic Channel Allocation for Wireless Networks
Channel allocation schemes in a mobile computing (wireless) environment can be either static or dynamic. Static allocation offers negligible channel acquisition time and zero message complexity and works well at a low system load; the performance steadily decreases as system load increases since many calls are dropped. In the case of even temporary hot spots many calls may be dropped by a heavily loaded switching station even when there are enough idle channels in the interference region of that station. On the other hand, dynamic schemes provide better utilization of the channels at higher loads albeit at the cost of higher channel acquisition time and some additional control messages. Our purpose in the present paper is to propose a combined channel allocation scheme so that each switching station can tune to its own load independent of other stations in its interference region; the objective is to minimize the call drop rate and at the same time maintain a minimum average channel acquisition time and minimum control message complexity.
384064
Proximity based access control in smart-emergency departments
In this paper, we propose a proximity based automated access control (PBAC) model for smart-ED environments which improves the existing ED work-flow by automating mundane administrative procedure for secure information access, allowing caregivers to focus on the treatment of patients. The proposed access model builds on the traditional role-based access control model and extends it by including multiple authentication levels for preventing unauthorized access. We also provide a semi-formal specification for the PBAC model. We further validate it using ultra-wide-band (UWB) based prototype which was tested in ED
40067645
A BIST methodology for comprehensive testing of RAM with reduced heat dissipation
The severity of excessive heat dissipation during concurrent BIST of memory modules has been documented previously (1993). In this paper, the authors present new versions of several memory tests that reduce heat dissipation during testing. Each proposed test has the same fault coverage and time complexity as the original version but it reduces heat dissipation by a factor of two or more. For three of the tests, the heat dissipation is reduced by factors of four to sixteen. The design of BIST circuitry required to implement the proposed tests are presented and it is shown that additional area overhead incurred is very small.
5121481
Switch-level delay test of domino logic circuits
We address the testing of delay faults in domino circuits that contain complex gates. The different ways in which these faults can cause errors are demonstrated. We identify structures in both the evaluate and the precharge logic that should be tested for delay faults. We propose conditions to generate delay tests for them, and outline extensions to handle mixed static-domino circuits. Testability results are reported for benchmark circuits that are mapped to domino gates and in-house domino circuits.
8584813
Generation of alternative feature-based models and precedence orderings for machining applications
Incre=ing global competition is challenging the U.S. manufacturing industry to bring competitively-priced, well-designed and well-manufactured products to market in a timely fashion. Since decisions made during the design stage can have significant effects on product cost, quality, and lead time, increasing research attention is being given to integrating engineering design and manufacturing, with a focus on design for manufacturability. Consider the task of designing and manufacturing machined parts. Often there can be several different ways to machine a part. Which way is best depends on several factors, including dimensions, tolerances, surface finishes, availability of machine tools and cutting tools, fixturability, and optimization criteria. Thus, to evaluate the manufacturability of the proposed design, we may need to consider more than one way to machine it. This paper outlines our approach for generating and evaluating alternative ways to machine a part. For additional details, see [1]; for other related work, see [2, 3].
1246119
Interface synthesis using memory mapping for an FPGA platform
Several system-on-chip (SoC) platforms have recently emerged that use reconfigurable logic (FPGAs) as a programmable coprocessor to reduce the computational load on the main processor core. We present an interface synthesis approach that forms part of our hardware-software codesign methodology for such an FPGA-based platform. The approach is based on a novel memory mapping algorithm that maps data used by both the hardware and the software to shared memories on the reconfigurable fabric. The memory mapping algorithm couples with a high-level synthesis tool and uses scheduling information to map variables, arrays and complex data structures to the shared memories in a way that minimizes the number of registers and multiplexers used in the hardware interface. We also present three software schemes that enable the application software to communicate with this hardware interface. We demonstrate the utility of our approach and study the trade-offs involved using a case study of the codesign of a computationally expensive portion of the MPEG-1 multimedia application on to the Altera Nios platform.
18442431
Understanding the Balanced Effects of Belief and Feeling on Information Systems Continuance
There are innumerable studies on technology adoption as well as continuance of usage. A review of previous research shows that cognitive factors are considered prominently in information technology adoption and continuance while the affective feelings of users are not. Although attitude and user satisfaction are common factors considered in information systems research, these factors only involve partial aspects of feelings. Researchers in the marketing areas, as well as the psychology area, begin to note the importance of feelings in understanding and predicting human and customer behavior. In many modern applications, such as mobile Internet services, user feelings are expected to be important, since users are not just technology users but also service consumers. Drawing upon the support of consumer research, social psychology, and computer science, this study proposes a balanced belief–feeling model of IS continuance. In the process of developing this model, the concepts of attitude, belief, and feelings are further articulated, defined, and distinguished. The balanced model is tested in a survey of mobile Internet users. The results established the validity of the model. A comparison with the IS continuance model shows that the new model can explain significantly more variance in continuance intention, taking into account that the new model has more factors. We offer theoretical reasoning for the balanced effects of belief and feeling on IS continuance and discuss the theoretical and practical implications of this study.