Packet scheduling in third generation mobile systems with UTRA-TDD air interface

4noUTRA-TDD is one of the adopted air interfaces for third-generation mobile communication systems (UMTS). In UTRA-TDD, information packets are transmitted organized into radio frames. A radio frame is divided into a fixed number of time slots and different packets can be sent on the same time slot by means of the Code Division Multiple Access technique. Packets belong to different traffic classes and have different formats and Quality of Service (QoS) requirements in terms of delay, transmission error probability and priority level. In this paper, we address the problem of scheduling packets for downlink transmissions in the time slots of a frame, in such a way that QoS requirements are fulfilled. In particular, exact pseudo-polynomial and heuristic scheduling algorithms are compared in terms of typical performance parameters. Computational results for three traffic classes show that the proposed algorithms are suitable for UTRA-TDD implementation, both for solution quality and computational time.reservedmixedCiaschetti, G.; Corsini, L.; Detti, P.; Giambene, G.Ciaschetti, Gianfranco; Corsini, L.; Detti, Paolo; Giambene, Giovann

Optimization of Access to CDMA Networks

Cílem dizertační práce je optimalizace přístupu do sítí CDMA (Code Division Multiple Access). Práce se konkrétně zabývá algoritmy pro řízení přístupu do sítě pro systém UMTS (Universal Mobile Telecommunication System). V úvodní části je pozornost zaměřena na popis dosavadního vývoje dané problematiky a následně je provedena analýza řízení přístupu do sítě UMTS. V programu MATLAB byl vytvořen vlastní model systému UMTS, který umožňuje implementovat vybrané algoritmy přístupu do sítě. Pozornost byla zaměřena na algoritmy, které využívají činitel zatížení, fuzzy logiku a genetické algoritmy. Všechny algoritmy byly s pomocí vytvořeného simulačního programu vzájemně porovnány. Cílem práce je vytvořit vhodný simulační program, prozkoumat vlastnosti jednotlivých algoritmů a případně provést jejich optimalizaci.The aim of this dissertation thesis is an optimization of access to CDMA networks. To be more specific, this thesis deals with an optimization of admission control in UMTS network. The first part of the thesis deals with the present progress of the particular topic. Thereinafter there is an analysis of admission control in UMTS system. An own UMTS simulation program was created in MATLAB. This program enables implementation and simulation of the selected admission control algorithms. The thesis is focused on load factor based, fuzzy logic based and genetic algorithms. The created UMTS simulator was used for the mutual comparison of all algorithms. The aims of this thesis are the suitable UMTS model design, evaluation and possible optimization of selected algorithms.