Performance Bound (performance + bound)

Distribution by Scientific Domains


Selected Abstracts


Performance analysis of dynamic channel assignment algorithms in cellular mobile systems with hand-off

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 8 2002
L. Cong
Abstract In this paper, the traffic performance of dynamic channel assignment (DCA) in cellular mobile system with hand-off is investigated. A traffic model for cellular system incorporating hand-off is established first. Under the framework of the model, a hand-off priority scheme is developed to reduce the forced termination of calls in progress. This paper analyses and derives the traffic performance bound for DCA strategies with hand-off by extending the maximum packing (MP) scheme to include the hand-off procedure. For practical implementation, a distributed DCA algorithm (DDCA) is also proposed. A non-priority scheme and the proposed priority scheme can be combined with either MP or DDCA. It is shown that the simulation results of DDCA scheme are comparable with the analytical bounds given by MP for both the non-prioritized case and prioritized case. A reasonable trade-off between the new call blocking probability and forced termination probability can be achieved by using the proposed prioritized scheme in DCA. Copyright © 2002 John Wiley & Sons, Ltd. [source]


Effectiveness and limitation of circle criterion for LTI robust control systems with control input nonlinearities of sector type

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 17 2005
Tsuyoshi Kiyama
Abstract This paper considers linear time invariant systems with sector type nonlinearities and proposes regional ,2 performance analysis and synthesis methods based on the circle criterion. In particular, we consider the effect of non-zero initial states and/or an ,2 disturbance inputs on the ,2 norm of a selected performance output. We show that both analysis and synthesis problems can be recast as linear matrix inequality (LMI) optimization problems, where, for synthesis, the outputs of the nonlinear elements are assumed available for control. Moreover, it is shown when the circle criterion does or does not help to improve the performance bound in robust control synthesis when compared with the existing linear analysis method. Copyright © 2005 John Wiley & Sons, Ltd. [source]


PID control performance assessment: The single-loop case

AICHE JOURNAL, Issue 6 2004
Byung-Su Ko
Abstract An iterative solution is developed for the calculation of the best achievable (minimum variance) PID control performance and the corresponding optimal PID setting in an existing control loop. An analytic expression is derived for the closed-loop output as an explicit function of PID setting. The resulting benchmark allows for realistic performance assessment of an existing PID control loop, especially when the control loop fails to meet the minimum variance performance. A PID performance index is then defined based on the PID performance bound, and its confidence interval is estimated. A series of simulated examples are used to demonstrate the utility of the proposed method. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1211,1218, 2004 [source]


Warehouse sizing to minimize inventory and storage costs

NAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 4 2001
Mark Goh
Abstract This paper considers a warehouse sizing problem whose objective is to minimize the total cost of ordering, holding, and warehousing of inventory. Unlike typical economic lot sizing models, the warehousing cost structure examined here is not the simple unit rate type, but rather a more realistic step function of the warehouse space to be acquired. In the cases when only one type of stock-keeping unit (SKU) is warehoused, or when multiple SKUs are warehoused, but, with separable inventory costs, closed form solutions are obtained for the optimal warehouse size. For the case of multi-SKUs with joint inventory replenishment cost, a heuristic with a provable performance bound of 94% is provided. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 299,312, 2001 [source]


Reliable State Feedback Control Synthesis For Uncertain Linear Systems

ASIAN JOURNAL OF CONTROL, Issue 2 2003
Guang-Hong Yang
ABSTRACT This paper is concerned with the problem of designing reliable state- feedback control for a class of uncertain linear systems with norm bounded uncertainty. A procedure for designing reliable state-feedback control is presented for the case of actuator faults that can be modeled by a scaling factor. In the design, the performance of the normal system (without fault) is optimized, as the considered system operates under the normal condition most of the time. In addition, when actuator faults occur, the closed-loop system retains robust stability and satisfies a known quadratic performance bound. A numerical example is provided to illustrate the effectiveness of the proposed design method. [source]


On parameter estimation of a simple real-time flow aggregation model

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2006
Huirong Fu
Abstract There exists a clear need for a comprehensive framework for accurately analysing and realistically modelling the key traffic statistics that determine network performance. Recently, a novel traffic model, sinusoid with uniform noise (SUN), has been proposed, which outperforms other models in that it can simultaneously achieve tractability, parsimony, accuracy (in predicting network performance), and efficiency (in real-time capability). In this paper, we design, evaluate and compare several estimation approaches, including variance-based estimation (Var), minimum mean-square-error-based estimation (MMSE), MMSE with the constraint of variance (Var+MMSE), MMSE of autocorrelation function with the constraint of variance (Var+AutoCor+MMSE), and variance of secondary demand-based estimation (Secondary Variance), to determining the key parameters in the SUN model. Integrated with the SUN model, all the proposed methods are able to capture the basic behaviour of the aggregation reservation system and closely approximate the system performance. In addition, we find that: (1) the Var is very simple to operate and provides both upper and lower performance bounds. It can be integrated into other methods to provide very accurate approximation to the aggregation's performance and thus obtain an accurate solution; (2) Var+AutoCor+MMSE is superior to other proposed methods in the accuracy to determine system performance; and (3) Var+MMSE and Var+AutoCor+MMSE differ from the other three methods in that both adopt an experimental analysis method, which helps to improve the prediction accuracy while reducing computation complexity. Copyright © 2005 John Wiley & Sons, Ltd. [source]


An analytical simulator for deploying IP telephony

INTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 1 2009
K. Salah
Deploying IP telephony or voice over IP (VoIP) is a major and challenging task. This paper describes an analytical design and planning simulator to assess the readiness of existing IP networks for the deployment of VoIP. The analytical simulator utilizes techniques used for network flows and queuing network analysis to compute two key performance bounds for VoIP: delay and bandwidth. The simulator is GUI-based and has an interface with drag-and-drop features to easily construct any generic network topology. The simulator has an engine that automates and implements the analytical techniques. The engine determines the number of VoIP calls that can be sustained by the constructed network while satisfying VoIP QoS requirements and leaving adequate capacity for future growth. As a case study, the paper illustrates how the simulator can be utilized to assess the readiness to deploy VoIP for a typical network of a small enterprise. We have made the analytical simulator publicly available in order to improve and ease the process of VoIP deployment. Copyright © 2008 John Wiley & Sons, Ltd. [source]


The sequential sum problem and performance bounds on the greedy algorithm for the on-line Steiner problem

NETWORKS: AN INTERNATIONAL JOURNAL, Issue 3 2005
Zevi Miller
Abstract This article is motivated by versions of the dynamic or "on-line" Steiner tree problem (OST) introduced by Imase and Waxman [4]. In this problem one is given an edge-weighted graph G and a sequence , = (x1,,,xn) of distinct vertices of G. The requirement is to construct for each i , n a tree Ti spanning the first i vertices of , subject to the condition that Ti,1,Ti for all i, where Ti is constructed without knowledge of the remaining vertices xj, j > i. The goal of the on-line Steiner problem is to minimize the performance ratio; that is, the maximum (over 1 , i , n) of the ratio of the weight of Ti to the weight of the minimum weight tree in G spanning the first i vertices (the latter tree is called the "Steiner tree" for these vertices). In [4] a lower bound of 1 + ˝, log2(n,1), was proved for this ratio. The authors further made the interesting conjecture that there is some on-line algorithm for the OST whose performance ratio achieves this lower bound. We show that a strong form of the greedy algorithm achieves a ratio that converges to the conjectured ˝log2(k) + O(1) as the proportion of degree 2 vertices in the instance graph grows. Our results also imply improvements in certain cases on the known upper bound ,log2(n), for the performance ratio of the greedy algorithm. Our approach is to study a related graph parameter. For each sequence , as above, define the associated cost where c(i,,) = min1 , t < idist(xi, xt). Then let Opt(n, G) be the maximum of L(,) over all such sequences , of length n. The problem of, given n and G, determining Opt(n, G) we call the Sequential Sum Problem (SSP). In this article we analyze the SSP, obtaining exact values and bounds on Opt(n, G) and relating these bounds to the greedy algorithm for the OST. For example, we calculate Opt(n, P) for the path P, and obtain a surprising characterization of all length n sequences , which realize Opt(n, P). By analyzing Opt(n, P) for the "continuous" path, we derive upper bounds on the performance ratio of the greedy algorithm for the OST in arbitrary graphs. On the other hand, generalizing the lower bound argument of [4] we show that there are instances of OST, which can significantly "fool" any on-line algorithm for OST. Specifically, given any tree T normalized to have total edge weight 1, we construct a graph G and a length k , |V(T)| sequence , of vertices of G for which the performance ratio of any on-line algorithm for the OST with input , is lower bounded by Opt(k, T). Finally, we show that the SSP for arbitrary G is NP-complete. © 2005 Wiley Periodicals, Inc. NETWORKS, Vol. 45(3), 143,164 2005 [source]