Modeling Fault Coverage of Random Test Patterns

We present a new probabilistic fault coverage model that is accurate, simple, predictive, and easily integrated with the normal design flow of built-in self-test circuits. The parameters of the model are determined by fitting the fault simulation data obtained on an initial segment of the random test. A cost-based analysis finds the point at which to stop fault simulation, determine the parameters, and estimate fault coverage for longer test lengths. Experimental results on benchmark circuits demonstrate the effectiveness of this approach in making accurate predictions at a low computational cost. As compared to the cost of fault-simulating all the test vectors, the savings in computational time for larger circuits ranged from four to fourteen times. We also present an analysis of the mean and the variance of the fault coverage achieved by a random test of a given length. This analysis and simulation results demonstrate that while the mean coverage is determined by the distribution of the detectabilities of individual faults, the dual distribution of fault coverage of individual test vectors determines the variance.     

Lighting fibers in a dark network

We consider the problem of network design in transparent, or clear channel, optical networks associated with wavelength-division multiplexing (WDM). We focus on the class of traffic engineering models known as routing, wavelength, and capacity assignment problems. Here, in contrast to traditional networks, traffic flow paths must also be assigned an end-to-end wavelength. This additional requirement means that there can be an increased cost associated with optimal capacity allocations for such WDM-flows. In general, this can be arbitrarily worse than traditional network designs. We argue that in order to evaluate the benefit of different switch technologies, a good benchmark is to measure the increase in costs purely in terms of link capacity, we call this the cost of transparency. Experimental research shows that this cost is small in multifiber networks with modest switching functionality at the nodes. We present theoretical justification for why this occurs, and prove that in multiwavelength multifiber transparent networks the cost of transparency all but disappears if there is moderate traffic load. Our arguments are based on efficient heuristics that may also be useful for more complex network optimizations. This suggests that the cost savings from using wavelength converters is significant only in young networks with relatively few fibers lit. Such savings may, thus, be small relative to the initial capital expense involved in installing wavelength conversion.     

Survivable MPLS Over Optical Transport Networks: Cost and Resource Usage Analysis

In this paper we study different options for the survivability implementation in MPLS over optical transport networks (OTN) in terms of network resource usage and configuration cost. We investigate two approaches to the survivability deployment: single layer and multilayer survivability and present various methods for spare capacity allocation (SCA) to reroute disrupted traffic. The comparative analysis shows the influence of the offered traffic granularity and the physical network structure on the survivability cost: for high bandwidth LSPs, close to the optical channel capacity, the multilayer survivability outperforms the single layer one, whereas for low bandwidth LSPs the single layer survivability is more cost-efficient. On the other hand, sparse networks of low connectivity parameter use more wavelengths for optical path routing and increase the configuration cost, as compared with dense networks. We demonstrate that by mapping efficiently the spare capacity of the MPLS layer onto the resources of the optical layer one can achieve up to 22% savings in the total configuration cost and up to 37% in the optical layer cost. Further savings (up to 9 %) in the wavelength use can be obtained with the integrated approach to network configuration over the sequential one, however, at the increase in the optimization problem complexity. These results are based on a cost model with different cost variations, and were obtained for networks targeted to a nationwide coverage     

Efficient full-wave modeling of patch antenna arrays with new single-layer capacitive feed probes

This paper introduces a new variation on the capacitive feed probe for patch antennas on thick substrates. It consists of a small circular probe-fed capacitor patch that is situated next to the resonant patch. This configuration can bring about significant savings in terms of manufacturing cost, but also lends itself to a very efficient full-wave analysis. As such, the main focus of this paper is a spectral-domain moment-method formulation, which was specifically developed for the analysis of large, but finite, arrays of these antenna elements. Entire-domain and subdomain basis functions are combined in an efficient way to minimize the computational requirements, most notably computer memory. It is shown that, for general antenna array configurations, memory savings of more than 1000 times can be achieved when compared with typical commercial software packages where only subdomain basis functions are used. A number of numerical and experimental results are also included in order to verify the spectral-domain moment-method formulation and to illustrate various applications of the new antenna element.     

Influence of modularity and economy-of-scale effects on design of mesh-restorable DWDM networks

This work is motivated by interest in restorable mesh architectures for WDM optical networking DWDM technology is expected to create an extremely modular capacity-planning situation and to produce potentially strong nonlinear economy-of-scale effects in capacity. How will this influence the design of cost-optimized mesh-restorable networks? Will it be essential to do true modular design optimization, or will the traditional rounding-up procedure still be adequate? Can a true modular design method exploit these effects for capital cost savings in the network design? What influence would strong modularity and economy-of-scale have on the evolution of the fiber facilities graph topology for these networks? We address these questions with three mathematical programming formulations that allow a comparative study of these issues in terms of the cost and architectural differences between networks designed with different treatments of the modularity issue. Results show that there are worthwhile savings to be had by bringing modularity aspects directly into the basic design formulation, rather than postmodularizing a continuous integer result, as done in most prior practice. The most significant research finding may be the demonstration of topology reduction (or paring down of the facilities graph) arising spontaneously in optimized designs under the combined effects of high modularity and economy-of-scale. This is the first quantitative indication and explanation of why less highly connected graph topologies may be preferred (at least from an economic standpoint) in future WDM networks, even though the spare capacity efficiency for mesh-based restoration is improved by higher connectivity.     

Sharing the “cost” of multicast trees: an axiomaticanalysis

Given the need to provide users with reasonable feedback about the “costs” their network usage incurs and the increasingly commercial nature of the Internet, we believe that the allocation of cost among users will play an important role in future networks. This paper discusses cost allocation in the context of multicast flows. The question we discuss is this. When a single data flow is shared among many receivers, how does one split the cost of that flow among the receivers? Multicast routing increases network efficiency by using a single shared delivery tree. We address the issue of how these savings are allocated among the various members of the multicast group. We first consider an axiomatic approach to the problem, analyzing the implications of different distributive notions on the resulting allocations. We then consider a “one-pass” mechanism to implement such allocation schemes and investigate the family of allocation schemes such mechanisms can support     

Affordable Mobile TV Services in Hybrid Cellular and DVB-H Systems

Mobile TV services are expected to become a key application in future wireless networks. The recently proposed terrestrial digital broadcast technology, DVB-H, especially designed for mobile services, is regarded as a powerful alternative to the 3G cellular networks that already offer these services out on a point-to-point basis. Unfortunately, the cost of supporting real-time streaming and full area coverage seems to be very high compared to fixed TV services. In this article we discuss hybrid IP datacast DVB-H and 3G systems as a possible solution for providing affordable network infrastructure and services. Our approach is DVB-H centric. The 3G cellular system plays the role of providing interactivity, error reporting, and repair for the DVB-H broadcast channel. To enable an easy and efficient interworking of DVB-H and 3G, we employ forward error correction at the application layer with digital fountain coding. The main way to provide lower cost services is to avoid full DVB-H area coverage from the beginning and to perform an incremental DVB-H network deployment that follows the user demand. In this direction, to hide the discontinuity in coverage from the perception of users, we propose to take advantage of the bursty character of DVB-H transmissions and the mobility of users. This is possible by sending additional parity data, either with the DVB-H or the cellular network, in the time intervals between original service bursts. We evaluate the potential DVB-H infrastructure cost savings determined by transmitting additional parity data in DVB-H when targeting vehicular users. The implications of delivering parity data through the cellular network also are discussed. The numerical investigations show a potential for significant cost savings compared with the traditional approaches     

Minimizing energy consumption in large-scale sensor networks through distributed data compression and hierarchical aggregation

In this paper, we study how to reduce energy consumption in large-scale sensor networks, which systematically sample a spatio-temporal field. We begin by formulating a distributed compression problem subject to aggregation (energy) costs to a single sink. We show that the optimal solution is greedy and based on ordering sensors according to their aggregation costs-typically related to proximity-and, perhaps surprisingly, it is independent of the distribution of data sources. Next, we consider a simplified hierarchical model for a sensor network including multiple sinks, compressors/aggregation nodes, and sensors. Using a reasonable metric for energy cost, we show that the optimal organization of devices is associated with a Johnson-Mehl tessellation induced by their locations. Drawing on techniques from stochastic geometry, we analyze the energy savings that optimal hierarchies provide relative to previously proposed organizations based on proximity, i.e., associated Voronoi tessellations. Our analysis and simulations show that an optimal organization of aggregation/compression can yield 8%-28% energy savings depending on the compression ratio.     

Topology/Floorplan/Pipeline Co-Design of Cascaded Crossbar Bus

On-chip bus design has a significant impact on the die area, power consumption, performance and design cycle of complex system-on-chips (SoCs). Especially, for high frequency systems having on-chip buses pipelined extensively to cope with long wire delay, a naive bus design may yield a significant area/power cost mostly due to bus pipeline cost. The topology, floorplan, and pipeline are the most important design factors that affect the cost and frequency of the on-chip bus. Since they are strongly correlated with each other, it is imperative to codesign all of the three. In this paper, we present an automated codesign method for cascaded crossbar bus design. We present CADBUS (CAscadeD crossbar BUS design tool), an automated tool for AXI-based cascaded crossbar bus architecture design. The primary objective of this study is to design a cascaded crossbar bus, including the topology/floorplan/bus pipelines, having minimum area/power cost while satisfying the given constraints of communication bandwidth/latency or frequency. Experimental results of the three industrial strength SoCs show that, compared to the existing approach, the proposed method gives as much as 11.6%–34.2% (9.9%–33.5%) savings in bus area (power consumption).      

Cooperative Routing in Static Wireless Networks

We study the problem of transmission-side diversity and routing in a static wireless network. It is assumed that each node in the network is equipped with a single omnidirectional antenna and that multiple nodes are allowed to coordinate their transmissions in order to obtain energy savings. We derive analytical results for achievable energy savings for both line and grid network topologies. It is shown that the energy savings of and are achievable in line and grid networks with a large number of nodes, respectively. We then develop a dynamic-programming-based algorithm for finding the optimal route in an arbitrary network, as well as suboptimal algorithms with polynomial complexity. We show through simulations that these algorithms can achieve average energy savings of about in random networks, as compared to the noncooperative schemes.     

Moore's Law and energy and operations savings in the evolution of optical transport platforms

As a telecommunications equipment vendor, we have witnessed a tremendous increase in the capacity of transport equipment over the past 16 years. Platforms have evolved from the firstgeneration add/drop multiplexer to the next generation multiservice provisioning platform and today's packet optical transport platform. This article discusses our findings in the application of Moore's Law to these optical transport platforms in capacity, power, space, and capital cost. It also discusses our findings in using Moore's Law as a presumption to explore the operations cost savings in power consumption, office floor space, and maintenance. Payback periods for the capital cost of new technology from energy and operations savings are investigated. The conclusions justify the replacement of the network technology for every other generation.     

An Economic Analysis of Local Digital Time Division Exchange Networks

Digital time division switching may lead to important savings in local exchange areas experiencing high growth rates, digital trunk or subscriber carrier penetration and a large demand for special services. To capture these savings a wire center design with integrated pair gain and special services systems, as well as operational support systems, is postulated. Wire center savings are primarily the result of a reduction in the getting started cost of the assumed switch, a reduction in central office hardware with digital trunking and digital pair gain systems, a reduction in outside plant costs, a reduction in special service equipment through integration of switching and transmission treatment functions, a reduction in main distributing frame size and a reduction in operations expenses. These results are based on a "paper design" of a digital time division switch with projected cost profiles which may not be realizable in the near future.     

Reduction in the cost of solving an integral equation arising in electromagnetic scattering through the use of group theory

An analysis is given of the use of symmetry groups in reducing the cost of some electromagnetic field calculations. The savings is obtained by reducing the size of a matrix arising in the discretization of an integral equation describing electromagnetic fields induced in penetrable obstacles.     

The Impacts of an Electronic Marketplace with Multiple Independent Retailers for Smart Grocery Ordering Systems

This study investigates the impacts of an electronic marketplace with multiple independent retailers for a smart grocery ordering system. Apart from replenishing products from suppliers, the system can also purchase/sell products from/to the electronic marketplace through ‘spot shops’. Both static and dynamic pricing models for the electronic marketplace are developed. An extensive numerical experiment is conducted and the results show that under both static and dynamic pricing, (i) the inventory cost of the aggregated supply chain is significantly reduced; (ii) each participant also enjoys significant cost savings from employing the electronic marketplace. Furthermore, the cost savings increase as the lead times from suppliers increase and/or the variability of their demands increases. The participants’ cost savings also increase as more participants employ the electronic marketplace.     

Evaluation of capacity planning practices for the semiconductor industry

We perform four experiments to evaluate several features of capacity planning approaches used in practice and make concrete suggestions for practitioners. We use an optimal capacity planning technique (FIFEX) with industrial demand and capacity data for realistic conclusions. The first experiment studies the cost effects of allowing for capacity expansion only at special times such as at the beginning of each month or each quarter. We find that these effects are not great if there is at least one capacity expansion opportunity about every six months. The second experiment determines the cost implications of capacity planning heuristics. We demonstrate that FIFEX delivers solutions which cost 5-10% less than heuristic solutions. The third experiment examines the sensitivity of costs against the frequency of forecasting and planning. Our experiments indicate that costs can be decreased by 2%-7% by doubling forecasting and planning frequency. We suggest that practitioners forecast and plan at least once every quarter. The final experiment compares joint optimization of tool and floor-shell expansions with sequential optimization. 3%-9% of costs can be saved by using the joint optimization technique FIFEX instead of sequential optimization. We note that although cost savings are relatively small in percentages, they correspond to tens of million dollars.     

The application of acoustic ranging to the automatic control of a ground vehicle

The use of acoustics is proposed as an alternative method to determine the position of a vehicle relative to the road or to other vehicles. Acoustic transducers mounted on the vehicle would range to passive targets along the side of the road or to other vehicles. The simplicity of the system indicates that it could offer potential advantages in cost savings. Factors which affect the accuracy of the system are discussed. Theoretical and experimental analysis is presented to determine the extent to which these factors influence the accuracy of the system. Based on these results, acoustic ranging represents a feasible method for use in the automatic control of a ground vehicle.     

Adoption timing of new equipment with another innovationanticipated

In dynamic environments, decisions about adopting or replacing new equipment or processes are influenced by the expectation of further innovations in technology. This paper examines the issue of the time at which an equipment (vointage one) currently in use is to be replaced with better equipment (vintage two), in the face of uncertain future availability of even better equipment (vintage three). We present an operational model useful in making adoption timing decisions and then present results that offer interesting insights into the impact of uncertainty and output expansion on the adoption time of vintage two. First, we characterize the optimal adoption time of vintage two in terms of the operating costs of various vintages, switching costs between vintages, and the hazard rate for the time of appearance of vintage three. We indicate the conditions under which it is optimal to follow a “now or never” or a “wait and adopt” policy with respect to adoption of vintage two. Second, it is shown that output expansion need not always spur the adoption of innovations. In fact, under certain conditions, output expansion may delay adoption of vintage two, even though vintage two has a higher operating cost savings per unit fixed cost than vintage three. We indicate how important factors such as benefits of new technologies other than operating cost reductions, learning effects, changes in costs over time, and fixed operating costs can be incorporated in the model     

Design and implementation of low-energy turbo decoders

Turbo codes have been chosen in the third generation cellular standard for high-throughput data communication. These codes achieve remarkably low bit error rates at the expense of high-computational complexity. Thus for hand held communication devices, designing energy efficient Turbo decoders is of great importance. In this paper, we present a suite of MAP-based Turbo decoding algorithms with energy-quality tradeoffs for additive white Gaussian noise (AWGN) and fading channels. We derive these algorithms by applying approximation techniques such as pruning the trellis, reducing the number of states, scaling the extrinsic information, applying sliding window, and early termination on the MAP-based algorithm. We show that a combination of these techniques can result in energy savings of 53.2%(50.0%) on a general purpose processor and energy savings of 80.66%(80.81%) on a hardware implementation for AWGN (fading) channels if a drop of 0.35 dB in SNR can be tolerated, at a bit error rate (BER) of 10/sup -5/. We also propose an adaptive Turbo decoding technique that is suitable for low power operation in noisy environments.     

An optimized network service for teleaction services in Switzerland

Swiss Telecom PTT has launched an optimized communication service for applications with small data volumes. The service, which is overlaid on their existing packet-switched data network, is based entirely on international ISO and ITU-TS standards. This article describes the communication solution, the protocols, and some service aspects with regard to cost savings and international standards, and discusses present applications and possible future developments