ETD system

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Tesi etd-07022009-002436


Thesis type
Tesi di laurea specialistica
Author
CIACCI, PAOLO
URN
etd-07022009-002436
Title
Bit loading for next generation wireless OFDM systems: a "greedy" approach for goodput optimization
Struttura
INGEGNERIA
Corso di studi
INGEGNERIA DELLE TELECOMUNICAZIONI
Commissione
relatore Ing. Lottici, Vincenzo
relatore Ing. Stupia, Ivan
relatore Prof. Giannetti, Filippo
Parole chiave
  • AMC
  • 4G
  • OFDM
  • bit loading
  • next generation
  • wireless
  • goodput
  • greedy
  • optimization
Data inizio appello
20/07/2009;
Consultabilità
parziale
Data di rilascio
20/07/2049
Riassunto analitico
Technologies as MIMO and BIC-OFDM have proved attractive performance in harsh multipath scenarios, making them suitable candidates for satisfying the ambitious goals of next generation wireless communication systems. Such techniques require a great deal of parameters to be optimized, for providing the best performance in every possible scenario.<br>The purpose of this thesis is to investigate the performance that a wise bit distribution among the subcarriers of an OFDM system-or &#34;bit loading&#34;-making use of some CSI, could provide, relevant to that achievable by a system which employs a fixed modulation scheme. In doing this, we try to maximize the goodput, which represents the average number of bits belonging to error-free data received by unit of time.<br>As background, we review an heuristic technique called &#34;greedy algorithms&#34;, whose key feature is that of trying to arrive at a global optimal solution of a problem, through a series of locally optimal (greedy) choices of many subproblems. So we make use of this methodology for elaborating some iterative sub-optimal bit loading procedures, and by means of simulation tools, we show that their contribution to the raise of the goodput performance is remarkable.<br>The elaborated methods are based on a PER estimation made with the Link Quality Metric &#34;kESM&#34;, which has been proved to be a reliable link performance predictor, for multicarrier systems employing a variety of modulation schemes.
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