04221 Abstracts Collection -- Robust and Approximative Algorithms on Particular Graph Classes

From 23.05.04 to 28.05.04, the Dagstuhl Seminar 04221 ``Robust and Approximative Algorithms on Particular Graph Classes\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

Joint Base Station Scheduling

Consider a scenario where radio base stations need to send data to users with wireless devices. Time is discrete and slotted into synchronous rounds. Transmitting a data item from a base station to a user takes one round. A user can receive the data item from any of the base stations. The positions of the base stations and users are modeled as points in Euclidean space. If base station b transmits to user u in a certain round, no other user within distance at most k

Optimization Problems in Mobile Communication

In one way or another mobile phones have changed everyone’s life. Mobile communication networks made it possible to be connected and reachable even in the most remote places. A lot of research effort has been put lately in the planning and optimization of mobile networks. Network providers as well as users can only gain in efficiency and usability if the algorithmic optimization community provides them with efficient algorithmic solutions to the optimization problems raised by mobile communication networks. In this thesis, we analyze three different algorithmically interesting problems stemming from mobile telecommunication: the base station location with frequency assignment; the OVSF code assignment problem; and the joint base station scheduling problem. We propose a new solution technique to the problem of positioning base station transmitters and assigning frequencies to the transmitters

Ortaklaşa hücre zumlama, çizelgeleme ve kullanıcı ilişkilendirme

Capacity can be increased by employing small cells in future mobile networks. When small cells are considered, a large number of base stations have to be deployed. This approach enlarges network infrastructures and increases the amount of energy consumption. Traffic demand in a mobile network is not fixed in time or space, and it cannot be accurately predicted in advance. Network functions such as base station scheduling, cell zooming or user-to-base-station association can be dynamically controlled to conserve energy. Base station scheduling is defined as deciding whether or not to keep a base station active depending on traffic demand. The coverage area of a base station can be adapted to demand that is referred to as cell zooming. User-to-base-station association can be dynamically configured to adjust the load of base stations for reducing energy consumption. Most of the related work in the literature consider these problems separately. In this thesis, we present a joint base station scheduling, zooming and user association technique. The major contribution of this thesis is reducing power consumption by turning off redundant base stations and adapting transmit power of active base stations to network conditions for maintaining quality of service and satisfying users. We formulated the joint optimization problem with the objective of reducing energy consumption and enhancing user satisfaction. We validated the proposed technique by using MATLAB optimization toolbox. In this work, we reduced energy consumption by 47% in comparison to the state-of-the-art solution.M.S. - Master of Scienc