Cost reduction in location management using semi‐realtime movement information

This paper introduces a dynamic paging scheme based on the semirealtime movement information of an individual user, which allows a more accurate predication of the user location at the time of paging. In general, a realtime location tracking scheme may require complex control schemes and incur unacceptably high computation and messaging cost. Our proposed approach, namely the velocity paging scheme, relaxes the realtime constraints to semirealtime to provide a good combination of cost reduction and ease of implementation. The proposed velocity paging scheme utilizes semirealtime velocity information, namely velocity classes, of individual mobile terminals and dynamically calculates a paging zone (a list of cells to be paged) for an incoming call. Therefore, the total paging cost can be reduced due to the paging area reduction. Much consideration also has been given to reduce the complexity of the proposed scheme. As a result, it only requires minimal extra overhead and is feasible to implement in current cellular/PCS networks. The velocity paging can be combined with the movementbased registration or other registration schemes. Analytical and simulation results of the velocity paging and movementbased registration combination are provided to demonstrate the cost effectiveness of the scheme under various parameters in comparison with the location area scheme.     

Gaussian radial basis functions and inner product spaces

An approximation result is given concerning Gaussian radial basis functions in a general inner product space. Applications are described concerning the classification of the elements of disjoint sets of signals, and also the approximation of continuous real functions defined on all of ⁿ using radial basis function (RBF) networks. More specifically, it is shown that an important large class of classification problems involving signals can be solved using a structure consisting of only a generalized RBF network followed by a quantizer. It is also shown that Gaussian radial basis functions defined on ⁿ can uniformly approximate arbitrarily well over all of ⁿ any continuous real functionalf on ⁿ that meets the condition that |f(x)|0 as x.     

Novel Ion-Lens Configurations: A Further Step to 2-nm Ion-Beam Lithography

Composite axially symmetric immersion ion lenses are considered that consist of an electrostatic and a magnetic lens. For the first time, their performance is evaluated over the entire range of operating conditions: from the case of a zero magnetic field to the case of a zero ion energy on the target. Operating conditions are characterized in terms of = W _t/W ₀, where W ₀ is the energy of an ion at the boundary of the region in which the trajectories are parallel to the axis and W _t is that on the target. For the first time, simple analytical approximations are derived for C _c/r, C _s/r, f/r, and NI, where C _c is the chromatic-aberration coefficient, C _s is the third-order spherical-aberration coefficient, f is the focal distance, NI is the magnetomotive force of the coil, and r is the outer radius of the coil. The behavior of the four quantities is explored as a function of . The following conclusions are drawn: (i) The aberrations are maximum for a zero magnetic field. (ii) The aberration coefficients decrease monotonically with increasing NIand decreasing , the lens changing from an accelerating to a decelerating one. (iii) If , then C _s/r – ^1/4, C _c/r – ^1/6, f/r– ^1/3, and NI – ^–1/2. (iv) The lenses are suitable for resistless heavy-ion projection lithography and can provide 20 × 10¹¹ pixels of area 2 × 2 nm² for an exposed area of 3 × 3 mm². (v) Used in heavy-ion microprobe systems, the lenses could enable resistless lithography over much larger areas than existing equipment.     

Diagnostic simulation of stuck-at faults in combinational circuits

Two faults are said to be equivalent, with respect to a test set , iff they cannot be distinguished by any test in . The sizes of the corresponding equivalence classes of faults are used as a basis for comparing the diagnostic capability of two given test sets. A novel algorithm, called multiway list splitting, for computing the Equivalence Classes of stuck-at faults, in combinational (full scan) circuits, with respect to a given test set is presented. Experimental results presented show the algorithm to be more efficient than previously known algorithms based on decision diagrams and diagnosibility matrix.Portions of this work were presented in [1].Research Supported by NFS Grant No. MIP9102509.Research Supported by SRC Grant 93-DP-109.     

Surface-Photovoltage Measurement of Volume Electron Lifetime in p-Si Wafers

The problem of estimating the volume lifetime _v of minority carriers in p-type Si wafers by surface-photovoltage measurements is addressed. An experiment is conducted in order to ascertain the relationship between measured and actual values of _v. The measurements are carried out on circular specimens whose thickness is reduced from about 2000 to 450 m by stepwise etching. The specimens are cut from a Czochralski-grown rod, their actual values of _v ranging from 10 to 300 s. The surface recombination rate of minority carriers is determined on both sides of the specimens covered with native oxide, the sides differing in surface finish. The results of the experiment allow one to determine _v up to about 400 s.     

A VLSI decoder for a new type of constellations adapted to the Rayleigh Fading Channel

Diversity is the key solution to obtain efficient channel coding in wireless communications, where the signal is subject to fading (Rayleigh Fading Channel). For high spectral efficiency, the best solutions used nowadays are based on QAM constellations of 1-order diversity, associated with a binary code or a trellis coded modulation to increase the overall diversity. It has been shown that a new class of d-dimensional non-QAM constellations, named -constellations, can bring a d-order diversity without the addition of redundancy. Combined with classical coding techniques, -constellations are very efficient. However, the decoding algorithm is far more complicated for -constellations than for QAM-constellations. A sub-optimal algorithm that allows the decoding of -constellations is proposed. An example of an application for a 4 bits/Hz/s spectral efficiency with a 4-D -constellation is given. The VLSI architecture of the decoder is described. The implementation leads to 72 K gates, a binary rate of 32 Mbits/s and a BER of 10^-3 for a SNR of 14 dB.     

Geometric properties of nonlinear networks containing capacitor-only cutsets and/or inductor-only loops. Part I: Conservation laws

This paper is the first in a two part sequence which studies nonlinear networks, containing capacitor-only cutsets and/or inductor-only loops from the geometric coordinate-free point of view of differentiable manifolds. Given such a nonlinear networkN, with °₀ equal to the sum of the number of independent capacitor-only cutsets and the number of independent inductor-only loops, we establish the following: (i) circuit theoretic sufficient conditions to guarantee that the set ⁰, of equilibrium points is a ₀-dimensional submanifold of the state space ofN; (ii) circuit theoretic sufficient conditions for the condition thatN has ₀ independent conservation laws and hence that through each point of the state space ofN, there passes a codimension ₀ invariant submanifold ^* of the network dynamics; (iii) circuit theoretic sufficient conditions to guarantee that the manifolds ^* and ⁰ intersect transversely.This work was supported by the Natural Sciences and Engineering Research Council of Canada, under Grant Number A7113, and by scholarships from the Natural Sciences and Engineering Research Council of Canada and the Ontario Provincial Government.     

A cost effective distributed location management strategy for wireless networks

The mobility feature of mobile stations (MSs) imposes a large burden on network traffic control as a result of location management. Design issues of location management include MS registration (updating) and call setup (paging). Previous approaches introduced several network topologies for updating and paging procedures, but most of them focused on a single problem: either updating optimization or paging optimization. In this paper, we design and integrate two mechanisms, distributed temporary location caches (TLCs) and distributed home location registers (HLRs), to reduce database access delay and to decrease network signaling traffic in both updating and paging for low power, low tier micro cellular systems. By using TLCs, our approach can improve the performance of updating and paging in comparison with previous approaches. Experimental results based on our analytic model show that our location management procedures have lower HLR access rate, lower registration cost, and lower call setup cost than other approaches.     

BT Middleware — software as infrastructure

BT Middleware has been in production use since 1987. Every working day a user population of 60 000 people execute 25 million transactions on systems that generate in excess of 70% of BTs revenues. BT Middleware is installed on 32 production mainframe instances.BT Middleware provides both a development and run-time environment for applications that is controlled and manageable. Application standards can be enforced providing reuse of common code as well as common look and feel user interfaces. The use of BT Middleware has allowed the rapid implementation of leading edge solutions to pressing business requirements and Middleware is evolving to allow BTs operational support systems (OSS) to participate seamlessly in complex distributed architectures.The future for BTs OSS lies in their ability to integrate with new applications developed on open systems platforms. BT Middleware has been evolving to provide the required interconnection capabilities and now supports numerous batch and on-line interfaces via strategic infrastructure products. This paper describes the major Middleware infrastructure components developed and supported by BTs London Software Engineering Centre that allow the companys huge investment in OSS to be exploited in todays environment.     

Quality Determination for Gate Delay Fault Tests Considering Three-State Elements

Most industrial digital circuits contain three-state elements besides pure logic gates. This paper presents a gate delay fault simulator for combinational circuits that can handle three-state elements like bus drivers, transmission gates and pulled busses. The well known delay faults--slow-to-rise and slow-to-fall--are considered as well as delayed transitions from isolating signal state high impedance to binary states 0 and 1 and vice versa. The presented parallel delay fault simulator distinguishes between non-robust, robust and hazard free tests and determines the quality of a test. Experimental results for ISCAS85/89 benchmark circuits are presented as well as results for industrial circuits containing three-state elements.     

A Novel EKF-Based Recovery in DS Scheme for DS/CDMA Systems Tracking Code Delay

Classical delay-lock loops (DLL) have beenwidely considered for code synchronization purposes inDS/CDMA systems, although they have not been devised foroperation when channel fading is present. This paper describes a new code synchronizationscheme based on a previously proposed extended Kalmanfilter (EKF) approach. The scheme proposed in this paperis able to operate under low signal-to-interference ratios (SIR), usual at the receiver input incellular CDMA mobile environments, and it outperformsthe behavior of previously proposed EKF-based schemes,which failed in such environments. Performance results under realistic mobile environment conditionsare shown in terms of the mean time to lose lock (MTLL)and the tracking error variance ² for a wide range ofSIR values and under Rayleigh fading. Moreover, the Cramer-Rao lower boundon ² is also computed inorder to validate the results obtained viasimulations.     

On the distribution of characteristics in bijective mappings

Differential cryptanalysis is a method of attacking iterated mappings based on differences known as characteristics. The probability of a given characteristic is derived from the XOR tables associated with the iterated mapping. If is a mapping : Z ₂ ^m , then for each , X, Y Z ₂ ^m the XOR table for gives the number of input pairs of difference X=X+X for which gp(X)+(X)=Y.The complexity of a differential attack depends upon two properties of the XOR tables: the density of zero entries in the table, and the size of the largest entry in the table. In this paper we present the first results on the expected values of these properties for a general class of mappings . We prove that if : Z ₂ ^m Z ₂ ^m is a bijective mapping, then the expected size of the largest entry in the XOR table for is bounded by 2m, while the fraction of the XOR table that is zero approaches e ^–1/2=0.60653. We are then able to demonstrate that there are easily constructed classes of iterated mappings for which the probability of a differential-like attack succeeding is very small.The author is presently employed by the Distributed System Technology Center, Brisbane, Australia.     

The prime and generalized nullspaces of right regular pencils

The classical notion of the -generalized nullspace, defined on a matrixA R ^n×n,where is an eigenvalue, is extended to the case of ordered pairs of matrices(F, G), F, G R ^m×nwhere the associated pencilsF – G is right regular. It is shown that for every C {} generalized eigenvalue of (F, G), an ascending nested sequence of spaces {P ⁱ ,i=1, 2,...} and a descending nested sequence of spaces {ie495-02 i=1, 2,...} are defined from the -Toeplitz matrices of (F, G); the first sequence has a maximal elementM ^* , the -generalized nullspace of (F, G), which is the element of the sequence corresponding to the index , the -index of annihilation of (F, G), whereas the second sequence has the first elementP ^* as its maximal element, the -prime space of (F, G). The geometric properties of the {M ⁱ ,i=1, 2,..., and {P ⁱ ,i=1, 2,...sets, as well as their interrelations are investigated and are shown to be intimately related to the existence of nested basis matrices of the nullspaces of the -Toeplitz matrices of (F, G). These nested basis matrices characterize completely the geometry ofM ^* and provide a systematic procedure for the selection of maximal length linearly independent vector chains characterizing the-Segre characteristic of (F, G).     

Fault diagnosis in reconfigurable VLSI and WSI processor arrays

A systematic efficient fault diagnosis method for reconfigurable VLSI/WSI array architectures is presented. The basic idea is to utilize the output data path independence among a subset of processing elements (PEs) based on the topology of the array under test. The divide and conquer technique is applied to reduce the complexity of test application and enhance the controllability and observability of a processor array. The array under test is divided into nonoverlapping diagnosis blocks. Those PEs in the same diagnosis block can be diagnosed concurrently. The problem of finding diagnosis blocks is shown equivalent to a generalizedEight Queens problem. Three types of PEs and one type of switches, which are designed to be easily testable and reconfigurable, are used to show how to apply this approach. The main contribution of this paper is an efficient switch and link testing procedure, and a novel PE fault diagnosis approach which can speed up the testing by at leastO(V^1/2) for the processor arrays considered in this paper, where V is the number of PEs. The significance of our approach is the ability to detect as well as to locate multiple PE, switch, and link faults with little or no hardware overhead.     

Symmetry relations in multidimensional Fourier transform pairs

A relation between the types of symmetries that exist in signal and Fourier transform domain representations is derived for continuous as well as discrete domain signals. The symmetry is expressed by a set of parameters, and the relations derived in this paper will help to find the parameters of a symmetry in the signal or transform domain resulting from a given symmetry in the transform or signal domain respectively. A duality among the relations governing the conversion of the parameters of symmetry in the two domains is also brought to light. The application of the relations is illustrated by a number of two-dimensional examples.Notation R the set of real numbers - R ^m R × R × ... × R m-dimensional real vector space - continuous domain real vector - L {¦ – _i , i = 1,2,..., m} - m-dimensional frequency vector - W { – _i ,i=1,2,..., m} - m-dimensional normalized frequency vector - _P {¦ – _i , i=1,2,...,m} - g(ol) g (₁,₂,..., _m ) continuous domain signal - () ( _{1 2},..., _m )=G (j ₁,j ₂,..., j _m ) Fourier transform ofg (ol) - (A,b,,,) parameters ofT- symmetry - N the set of integers - N ^m N × N × ... × N m-dimensional integer vector spacem-dimensional lattice - h(n) h (n ₁,.,n _m ) discrete domain signal - H() Fourier transform ofh (n) - v ₁,v ₂,..., v_m m sample-direction and interval vectors - V (v ₁ v ₂ ...v _m ) sampling basis matrix - [x]^* complex conjugate ofx - detA determinant ofA - X {x¦ – x _i , i=1,2,..., m} - A ^–t [A ^–1] ^t ,t stands for transpose This work was supported in part by the Natural Sciences and Engineering Research Council of Canada under Grant A-7739 to M. N. S. Swamy and in part by Tennessee Technological University under its Faculty Research support program to P. K. Rajan.     

On the structure of the privacy hierarchy

An N argument function f(x ₁,...,x _N ) is called t-private if a protocol for computing f exists so that no coalition of at most t parties can infer any additional information from the execution, other than the value of the function. The motivation of this work is to understand what levels of privacy are attainable. So far, only two levels of privacy are known for N argument functions which are defined over finite domains: functions that are N-private and functions that are (N – 1)/2-private but not N/2-private.In this work we show that the privacy hierarchy for N-argument functions which are defined over finite domains, has exactly (N + 1)/2 levels. We prove this by constructing, for any N/2 t N – 2, an N-argument function which is t-private but not (t + 1)-private.This research was supported by US-Israel Binational Science Foundation Grant 88-00282.     

The AROUND Architecture for Dynamic Location-Based Services

This paper presents a generic concept of location-based service as an abstraction for supporting the association between computational resources and location. The objective is to extend the advantages of service-based architectures to the development of location-based systems, thus providing a more open and extensible alternative to the vertical approaches typically used in this type of system. The novel AROUND architecture is proposed as an approach for supporting location-based services in the Internet environment. AROUND provides a service location infrastructure that allows applications to select services that are specifically associated with their current location. The architecture includes a flexible scope model that defines the association between services and location, and a service location infrastructure organised by spatial criteria and optimised for location-based queries. Based on a prototype implementation of this architecture, we have developed two case studies that illustrate the use of this approach for developing location-based systems. The overall results provide a valuable insight into the applicability of the architecture, and suggest that this model of location-based services can provide a useful approach for the development of a wide range of location-based applications.     

Demand re‐registration for PCS database restoration

In a Personal Communications Services (PCS) network, mobility databases such as Home Location Register (HLR) and Visitor Location Register (VLR) are utilized to support mobility management for Mobile Stations (MSs). If the location databases fail, the location information loss or corruption will seriously degrade the service offered to the subscribers. In this paper, we propose a new VLR failure recovery scheme called demand reregistration. In this scheme, the VLR broadcasts a reregistration request to all MSs after the VLR failure. When an MS receives the reregistration request, it sends a registration message to the VLR to recover the location record. Since all MSs will reregister after receiving the broadcasting request, traffic jam (and thus collisions) may occur. If a collision occurs, then the involved MSs must resend the registration messages. This paper studies the performance of demand reregistration by investigating how effectively the reregistration can recover the location record for an MS before the first MS call termination occurs. Our results indicate that demand reregistration can effectively recover VLR failure.     

Mobile User Tracking Using A Hybrid Neural Network

In this paper, a novel technique for location prediction of mobile users has been proposed, and a paging technique based on this predicted location is developed. As a mobile user always travels with a destination in mind, the movements of users, are, in general, preplanned, and are highly dependent on the individual characteristics. Hence, neural networks with its learning and generalization ability may act as a suitable tool to predict the location of a terminal provided it is trained appropriately by the personal mobility profile of individual user. For prediction, the performance of a multi-layer perceptron (MLP) network has been studied first. Next, to recognize the inherent clusters in the input data, and to process it accordingly, a hybrid network composed of a self-organizing feature map (SOFM) network followed by a number of MLP networks has been employed. Simulation studies show that the latter performs better for location management. This approach is free from all unrealistic assumptions about the movement of the users. It is applicable to any arbitrary cell architecture. It attempts to reduce the total location management cost and paging delay, in general.Kausik Majumdar Received the B.E. degree in Electronics & Telecommunication from Jadavpur University, Kolkata in 2003. He is presently studying for M.Tech. degree in Optoelectronics & Optical Communication from IIT Delhi. Research interests include optical communication, computer networks, semiconductor devices and neural networks.Nabanita Das received the B.Sc. (Hons.) degree in Physics in 1976, B.Tech. in Radio Physics and Electronics in 1979, from the University of Calcutta, the M.E. degree in Electronics and Telecommunication Engineering in 1981, and Ph.D in Computer Science in 1992, from Jadavpur University, Kolkata. Since 1986, she has been on the faculty of the Advanced Computing and Microelectronics unit, Indian Statistical Institute, Calcutta. She visited the department of Mathematik and Informatik, University of Paderborn, Germany, under INSA scientists exchange programme. She has co-authored many papers published in International journals of repute. She has acted as the co-guest Editor of the special issue on Resource Management in mobile, ad hoc and sensor networks of Microprocessors and Microsystems, by Elsevier. She has acted as program chair of International workshop on distributed computing, IWDC 2004, and also as co-editor of the proceedings to be published as LNCS by Springer. Her research interests include parallel processing, interconnection networks, wireless communication and mobile computing. She is a senior member of IEEE.     

Pervasive Home Environments

For decades, technologists have been promising the intelligent house. The vision is usually portrayed as a house filled with technology which will do the dweller's bidding and take all domestic drudgery out of their lives. The truly intelligent house is still some way off, but the emergence of broadband, availability of faster, smaller and ever cheaper computing equipment and a variety of wired and wireless network technologies are enabling technologies that bring this vision closer to reality. These technology trends lead to the concept that computing and other smart devices will become pervasive, fully networked and disappear into the infrastructure of the home. People will carry out their tasks unaware of the complexity of the infrastructure that supports their activities in much the same way as people today use mains electricity.This paper introduces these concepts and discusses the technological challenges to be overcome. We present our vision of the pervasive home environment where inhabitants can focus on tasks rather than the technology: I need to create X and send it to Y rather than I need to use this computer and this application which needs access to service A and resource B. Although this sounds simple, the environment needs to understand who I is, and who or what Y is. Appropriate permissions must be in place and resources allocated, if available. The most appropriate interface for the task and user must be determined.The pervasive, intelligent home will make available new ways to access and share information. It will herald new services, such as care and support of people in the home, entertainment, educational and security services. The final part of the paper discusses the commercial opportunities and challenges which must be met, not least the need for industry to agree on open standards and interfaces.