CDMA 셀룰러시스템에서의 전력제어에 관한 연구

학위논문(석사) - 한국과학기술원 : 경영과학과, 1995.2, [ vi, 59 p. ]CDMA cellular systems are expected to solve demand explosion by its large capacity. But its advantages including capacity improvement need some more complicated operations. Among these, power control on radio link is a fundamental one. That is, large capacity is obtained only if transmitters appropriately control their powers. Therefore many researches on this topic have been reported, but these studies concentrate only on the traffic channel, so powers of other channels including pilot channel are neglected or regarded implicitly as constants. As a result, cell boundary is unstable, even worse service-blank area may be occurred in the worst case. In this paper, we consider the power control models in which power of pilot channels are also taken into account. Power balancing problem and power minimization problem are introduced and formulated as a linear program and a nonlinear program, respectively. Next, a solution method for each of them is suggested. For the numerical experiment of the above models, various environments - large/small number of cells, uniform/nonuniform traffic and sparse/dense traffic, are considered. After a round of tests for the examples, it is found that given traffic, the power of pilot channel is usually constant over cells and that the power of traffic channels are mainly proportional to both traffic densities of cells and the average distances between mobiles and base-stations.한국과학기술원 : 경영과학과

광전달망의 설계 및 분석

학위논문(박사) - 한국과학기술원 : 경영공학전공, 2003.2, [ vi, 71 p. ]Design and analysis issues for current and future telecommunication/ Internet infrastructure are considered. Formulations of the problems and algorithms for them which are based on the mathematical programming approaches are presented. First, a new network design problem of stacking multiple BLSRs (Bidirectional Line Switched Ring) on a conduit ring is considered. This problem is of great concern to Telcos and ISPs, which however has not been seriously addressed as yet. This scarcity, despite the practical importance of resource-efficient BLSRs, may be attributed to the problem complexity. The problem has been formulated as a natural IP model and reformulated as a set-partitioning model via the column generation approach. An iterative solution method of alternating between two phases of generating and fixing columns was developed and experimented with demand graphs of six different and practical scales. Computational experience gained from hundreds of test problems strongly supports the real-world applicability of the proposed model and the solution method. Furthermore, the proposed solution framework is flexible enough to easily accommodate the real-world features like various ADM capacities or the other architecture (UPSR) by simply modifying the subproblem structure. An immediate extension of practical importance would be to stack both types of SHRs on a given conduit ring infrastructure. Second, a unified approach of stacking multiple SHRs of two types of architectures (UPSR and BLSR) is presented. A column generation algorithm is also developed and experimented the algorithm with various demand patterns. Computational results show that the optimal hybrid stacked SHR configuration is more cost-effective than either one-type-only configurations. Third, network approaches for MPLS traffic engineering is described in an online setting where future requests for bandwidth-guaranteed ingress-egress paths can be accommodated without rearranging existing paths. Ide...한국과학기술원 : 경영공학전공

A Dual-based Algorithm for Uncapacitated Ring Selection Problem Which Arises in Designing Regional Networks

We consider a network problem which arises in designing regional network with ring/ring topology. Given conduit network, demand, candidate ring topology, proposed URSP (Uncapacitated Ring selection Problem) determines set of rings which guarantee every demand flow at minimum cost. Also, we develop a dual based heuristic for URSP, and apply it to the real world problem

링/링 토폴로지를 갖는 SDH망의 구축에 관한 연구

SDH로 대표되는 광전송기술은 대용량, 높은 신뢰성을 특징으로 하기 때문에 간단한 형태의 망토폴로지를 갖게 되므로, 링크나 노드가 손상되었을 경우에 생기는 손실은 엄청나다. 따라서 어느 하나의 링크나 노드가 훼손되더라도 그대로 망을 운용할 수 있는 생존도(Survivability)에 대한 요구가 절실하다. 생존도를 고려한 광전송장비는, 링토폴로지(Ring Topology)를 지원하는 ADM (Add drop Multiplexing)과 메쉬토폴로지(Mesh Topology)를 지원하는 DCS(Digital Cross-connecting System)로 대별되며, 이들 각각을 이용하여 구성한 단일링, 또는 단일메쉬망 등의 기본망구조에 관한 연구는 상당히 축적되어 있다. 한편, 실제로 망구성에서 고려되는 링/링 토폴로지나 링/메쉬 토폴로지 등의 기본망의 결합구조에 관한 연구는 거의 이루어지지 못하고 있다. 본 연구에서는 링이 다수 연접한 링/링 토폴로지를 분석하고자 한다. 관로망과 수요가 주어져 있을 때, 이를 수용하는 다중링의 토폴로지와 수량을 결정하는 모형을 제시하며, 이에 대한 분석과 사례연구를 시행한다