32212919
Balancing loads on sonet rings with integer demand splitting
SONET Self Healing ring is one of the most intriguing schemes which provide survivability for telecommunication networks. To design a cost effective SONET ring it is necessary to consider load balancing problems by which the link capacity is determined. In this paper, we consider the load balancing problem in SONET ring when demand splitting is allowed only by integer. A bounded approximation to the optimal solution is presented and proved by employing the arc-demand matrix which represents the amount of demand routed on each arc. A very efficient algorithm is provided which always satisfies the optimality at termination. The algorithm iteratively decreases the maximum load by considering counter-clockwise routing of a demand which passes through the arc with maximum load. Justification of the algorithm is also provided.
14489935
Dynamic resource allocation for CDMA-TDD indoor wireless systems
Future wireless communication systems are expected to provide a broad range of multimedia services that have a significant traffic asymmetry between uplink and downlink. The code division multiple access-time division duplex (CDMA-TDD) system is a promising solution to cope with the problem of traffic asymmetry. However, the TDD system is subject to inter-cell interference compared to frequency division duplex (FDD) system. Since both uplink and downlink share the same frequency in TDD, uplink and downlink may interfere each other especially when neighboring cells require different rates of traffic load. Thus, the resource allocation among cells is an important issue in TDD. In this paper, the resource allocation in the CDMA-TDD is formulated as a mixed integer programming (MIP) problem. A dynamic resource allocation algorithm (DRAA) is provided that effectively solves the traffic asymmetry problem. The MIP problem is also solved by a well-known branch and bound procedure. Both the crossed slot and non-crossed slot allocation are examined and compared to the DRAA. Computational result shows that proposed DRAA gives a good performance as the traffic asymmetry increases between the uplink and downlink. Copyright Â© 2003 John Wiley & Sons, Ltd.
13953434
A design of multi‐layered location registration areas in microcellular systems
Multi‐layered location registration areas are considered to minimize the control signals at boundary cells in the microcellular systems. The decision of multi‐layered location registration (LR) areas is formulated as an integer programming problem by examining the regional subscriber densities, traffic flows and call arrival rates. By relaxing the constraints of forward and reverse control channels the problem is decomposed into a number of subproblems each of which corresponds to a layer. Each subproblem is solved via a modified graph partitioning algorithm. Feasible LR areas are obtained by considering the two relaxed constraints. Computational experiments are performed in a system with 80 microcells to investigate the performance of the proposed multi‐layer scheme. The simulation results indicate that the two‐layer scheme generally outperforms the one‐layer and three‐layer methods in view of control signals.
962689
Supporting Benefit-Oriented Retrieval for Data on Air
Battery power is always a limitation for using mobile devices to access information in a wireless environment. One of the ways to alleviate the problem is to let the device go into a doze (no-reaction or disconnection) mode periodically so as to let the battery energy last longer. Broadcast disk technology is becoming a popular method for data dissemination in a wireless information system. In this paper, we study from a mobile host’s viewpoint how to achieve the highest “benefit” if it listens to the broadcast discontinuously. We propose three fast and near optimal algorithms for the MH to retrieve the broadcast data.
15498629
Computer Recognition of Two Overlapping Parts Using a Single Camera
The combination of computer vision to recognize overlapping objects and computer-based robots to acquire, orient, and transport these objects will revolutionize manufacturing technology. The bin-picking application, where robots transport randomly scattered parts from a bin and place them on a conveyor with the proper orientation, will significantly improve and economize many manufacturing processes. Equipping the robot with "sight" and the ability to recognize overlapping objects is a first step in solving the bin-picking problem. Recently, many image processing techniques have been applied to the recognition of non-overlapping objects. 1,2 The most successful of these use histogram techniques for segmenting objects from the background and then finding local features such as holes, curves, and corners;3 gradient analysis and Laplacian derivatives for locating edges; 4 and chain-encoding for representing edges and boundaries." Engineers have also employed line-thinning , line-merging, tracking, smoothing , and filtering techniques for image enhancement and sharpening;' and Opinions, findings, and conclusions or recommnenda-dons expressed in this article are those of the authors. maximal cliques,7 template matching, edge-cues, 8 and local feature cues9 for recognizing the object, its position and orientation. (Several techniques are described in the glossary following this article.) A system that determines the position and orientation of non-overlapping objects, and passes that information to a PUMA robot arm for acquisition and transporation, has already been developed at the University of Michigan's Robotics Research Laboratory. The basic method employed by this system is quite similar to the SRI vision module. '0 It compares previously taught parameters (or features) such as the area, perimeter, ratio of perimeter squared divided by area, and a radial template with similar parameters from the image calculated in real time. This system and others like it have been successful in recognizing discrete parts; however, they show severe limitations when attempting to recognize overlapping parts. The major problem lies in segmenting the image II-distinguishing two overlap
205046494
Run-time support For parallel functional programming on shared-memory multiprocessors
Abstract The use of functional languages for parallel computing has been proposed for many years. Many functional languages were developed along with the design of new architectures such as data flow and reduction machines. In this article, we present a general model of a run-time system for a parallel functional language called SISAL, to be executed on shared-memory multiprocessors. The implementation of this run-time system is examined on two radically different architectures: a 32-way (symmetrical) VAX Research Multiprocessor M31 and a 4-way Cray X-MP system. To properly evaluate the effectiveness of SISAL on shared-memory multiprocessors, we suggest further research explore an interactive visual control mechanism that dynamically shows run-time behavior.
40553193
Tracking Mobile Users Utilizing Their Frequently Visited Locations
In wireless computing environment, the explosive growth of demand in communication bandwidth requires new schemes to effectively and efficiently locate users. The Basic HLR/VLR locating scheme does not exploit the fact that many mobile users' moving patterns are likely to be known. In this paper, we propose one locating scheme, the Frequently Visited Locations First (FVLF) scheme, to effciently locate a mobile user. This scheme avoids the high cost of querying the callee's HLR. The cost model of the proposed scheme is derived and the optimal number of prestored RAs is also found.
31179959
Improving location management for mobile users with frequently visited locations
Abstract In wireless computing environment, users’ mobility brings new challenges to traditional computing systems. The explosive growth of demand in communication bandwidth requires new schemes to effectively and efficiently locate users. The Basic HLR/VLR locating scheme does not exploit the fact that many mobile users’ (such as commuters’) moving patterns are likely to be known. In this paper, we propose one locating scheme, the frequently visited locations first (FVLF) scheme, to efficiently locate a mobile user. The FVLF scheme is proposed to prestore the RAs that a mobile user frequently visits according to the probabilities of the RAs that the mobile user may appear. When the system receives a call, these prestored RAs are examined first to locate the callee. This scheme can avoid the high cost of querying the callee’s HLR. The cost model of the proposed scheme is derived and the optimal number of prestored RAs is also found. Our evaluation shows that benefit does exist in various conditions by using this scheme.