5,013 research outputs found
PRIORITIZED CHANNEL ASSIGNMENT IN A CELLULAR RADIO NETWORK
No full textDimensioning procedures for prioritized channel assignment in a cellular radio network are considered. Under the cutoff priority discipline, the prioritized channel assignment procedures for a single cell and multicell system are formulated as nonlinear discrete capacity allocation problems. Exact incremental algorithms which efficiently solve the proposed problems are devised based on the properties of the blocking probabilities of new calls and handoff calls. Given the number of available frequency channels together with the arrival rates and the GOS for both types of calls in each cell, algorithm SP1 generates an optimal channel assignment which ensures priority for handoff calls. Given the arrival rates and distinct GOS's for new and handoff calls, algorithm SP2 finds the minimum number of channels required in each cell. Algorithm MP extends algorithm SP1 to a multicell system and provides the prioritized channel assignment for all cells in the system. Due to their simplicity, our algorithms run very fast and can be implemented adoptively in the practical systems. It is also shown that they are appropriate for the fair allocation of frequency channels among the cells throughout the entire system
Threshold-type call control under the outage restriction in a CDMA cellular system
No full textFor a CDMA system with a single carrier, we consider a call control policy at each cell, which gives priority to handoff calls over new calls while meeting the overall call quality. New calls are first under the call control of the threshold type, and then receive services together with the handoff calls but under the outage restriction guaranteeing a pre-specified call quality. An optimization model with such quality-guaranteeing constraints is formulated, which is to determine the threshold value for each cell, minimizing the new call blocking probability. We propose a solution heuristic, with which a number of simulations are conducted under a variety of traffic environments. The computational experiments evaluate the usefulness of our call control scheme in that handoff calls are given an appropriate level of priority while the system capacity is effectively utilized
An extended model for establishing dominance in multiattribute decisionmaking
No full textThis paper is concerned with the use of incomplete information about utilities and weights in multiattribute decisionmaking. Because of time pressure and/or lack of knowledge, a decision maker may only be able to provide incomplete information which might be expressed as a set of linear inequalities. If the decision maker's information on both weights and utilities is imprecisely identified, then the model for establishing pairwise dominance becomes a non-linear program. A method for obtaining non-dominated alternatives without solving the non-linear program is proposed using a simple weighted-additive function
OPTIMAL-DESIGN OF THE 2-LEVEL DISTRIBUTED NETWORK WITH DUAL HOMING LOCAL CONNECTIONS
No full textTo keep abreast of the ever-tightening robustness standards of communication services, we consider the topological design of the two-level network where a sufficient level of structural redundancy is imposed: the embedded backbone subnet is fully meshed and each user node is connected to two different backbone nodes. This complicated design problem for the dual homing full-mesh network is formulated as a 0-1 integer problem so that the key structural characteristics of the single homing network design model are carried over. By applying the usual dual-based solution procedure, we develop ours, which consists of three dual and one primal subprocedures. The computational experiments conducted with a variety of test problems illustrate the effectiveness of the proposed solution approach
Optimal design of a distributed network with a two-level hierarchical structure
No full textThis paper deals with the topological design of a network with a two-level hierarchical structure where the embedded backbone network is full-meshed and the local networks attached to it are of star type. The whole problem, unlike the conventional approaches partitioning it into two subproblems, is directly handled in such a general setting that both a backbone network and local access networks are to be simultaneously determined. We formulate this problem as a quadratic 0-1 programming model, and also propose an equivalent linearized version of the model. Based on the observation that the linearized model is a variant of the well established uncapacitated facility location problem, a dual-based solution procedure is developed and shown to be efficient from computing experiments which were done on a wide variety of problems with up to 50 backbone nodes and 50 user nodes. © 1992
Somatic mutations in epidermal growth factor receptor underlying complete responsiveness to gefitinib in a taiwanese female patient with metastatic adenocarcinoma of lung.
No full textA method for user-customized compensation of metamorphopsia through video see-through enabled head mounted display
No full textAdvances in Augmented Reality technologies and, particularly, the availability of video see-through enabled head mounted displays (HMD), are allowing to devise new strategies to help individuals with visual impairments in daily life. In this work, an approach is proposed to compensate a serious visual impairment, known as metamorphopsia, a vision disorder characterized by deformed images. The goal is to provide patients with a digitally restored visual field, through real-time processing of video see-through streams captured from the HMD. To this regard, we present two contributions, respectively, an interactive discrete modeling of patient's eye-specific vision distortion and a compensation of the latter by means of corresponding real-time counter-distortion of incoming frames. Our approach, indeed, maps each of the video streams acquired by the stereoscopic video see-through cameras aboard the headset on a 2D polygonal mesh which is then counter-warped by moving its vertices based on the previously built distortion model and then displayed, restored, on the HMD's screen. First user evaluations report promising results along with usability issues related to HMD technology. (c) 2021 Published by Elsevier B.V
Cost-minimizing construction of a unidirectional SHR with diverse protection
No full textThe widespread use of SONET technology makes the self-healing ring (SHR) architecture the most basic building-block in designing a large fiber-optic network which is not only survivable but also cost-effective, We address the design problem of placing a single SONET unidirectional ring with a single gateway hub in a region administered by a community of interest, Introduced for the purpose of further cost-saving in our problem setting is the flexibility that some offices, instead of being included in the ring, can be homed to the ring via two are-disjoint paths, Given the set of offices and potential arcs, the objective is then to determine at the minimum total cost both the ring location and the homing to the ring of its nonmember nodes. We formulate the problem as a mixed integer programming model and develop an efficient solution procedure by devising six improvement heuristics, Extensive computational experiments are conducted with input data instances selected from the data ranges of the real-world environments, The practical value of the solution procedure for network planners is well evidenced by its excellent and consistent performance of quickly generated good-quality solutions over various input data instances
Perturbation-minimizing frequency assignment in a changing TDMA/FDMA cellular environment
No full textA robust operation of assigning frequencies to requirements in a time-division multiple-access (TDMA) [or frequency-division multiple-access (FDMA)] cellular system should cope with environmental changes such as short-term demand rises and long-term capacity expansions while always keeping the required realignment process as simple as possible. In this paper, we consider the so-called perturbation-minimizing frequency assignment problem (PMFAP), the objective of which is to assign available frequencies for newly generated requirements with the minimum change in the existing frequency assignments while meeting the interference-related constraints. For PMFAP, we propose a heuristic algorithm based on the so-called B nu-D omega rearrangement technique, which can also be applied to the classic frequency assignment problem (FAP) with a slight modification. Two kinds of computational experiments, one for each of the above two problems, are performed to demonstrate the powerful features of the proposed solution method not only in its suitability for real-world frequency management, but also in solving the FAP
Recognition of simple splicing systems using SH-automaton
No full textSplicing language is the language which results from a splicing system. Splicing system was first introduced by Tom Head in 1987 as the mathematical model of systems of restriction enzymes acting on initial DNA molecules. Splicing languages are closely related to automata theory. Simple splicing systems can be recognized by SH-automata diagrams due to the regularity of splicing languages. SH-automaton defines exactly one language which is the language generated by the simple splicing system. In this paper, the concept of firm and maximal firm subwords are introduced. Some examples are then given to illustrate the maximal firm subwords of a word in a simple splicing system. Taking the SH-automata concept, which is a short compact way of encoding normal non-deterministic automata in the special case of SH systems, the maximal firm subwords of the initial words of an SH systems serve as the labels for the associated SH-automaton. Some examples which will show the maximal firm subwords of the words in the initial set I, the regular expression for the language generated by the given splicing system and the simplest non-deterministic automaton that recognizes the corresponding splicing system are also given
- …
