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Archivio digitale delle tesi discusse presso l’Università di Pisa

Tesi etd-07022009-002436


Tipo di tesi
Tesi di laurea specialistica
Autore
CIACCI, PAOLO
URN
etd-07022009-002436
Titolo
Bit loading for next generation wireless OFDM systems: a "greedy" approach for goodput optimization
Dipartimento
INGEGNERIA
Corso di studi
INGEGNERIA DELLE TELECOMUNICAZIONI
Relatori
relatore Ing. Lottici, Vincenzo
relatore Ing. Stupia, Ivan
relatore Prof. Giannetti, Filippo
Parole chiave
  • 4G
  • AMC
  • bit loading
  • goodput
  • greedy
  • next generation
  • OFDM
  • optimization
  • wireless
Data inizio appello
20/07/2009
Consultabilità
Non consultabile
Data di rilascio
20/07/2049
Riassunto
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.
The purpose of this thesis is to investigate the performance that a wise bit distribution among the subcarriers of an OFDM system-or "bit loading"-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.
As background, we review an heuristic technique called "greedy algorithms", 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.
The elaborated methods are based on a PER estimation made with the Link Quality Metric "kESM", which has been proved to be a reliable link performance predictor, for multicarrier systems employing a variety of modulation schemes.
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