Title page for etd-0804108-181143


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URN etd-0804108-181143
Author Chun-Hsien Pan
Author's Email Address No Public.
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Department Communications Engineering
Year 2007
Semester 2
Degree Master
Type of Document
Language English
Title Subspace-Based Semi-Blind Channel Estimation in Uplink OFDMA Systems
Date of Defense 2008-07-25
Page Count 55
Keyword
  • virtual carriers recovery (VCR) scheme
  • virtual carriers (VCs)
  • Orthogonal Frequency Division Multiple Access (OFDMA)
  • semi-blind channel estimation
  • subspace decomposition
  • Abstract This thesis investigates the semi-blind channel estimation in uplink (UL) of Orthogonal Frequency Division Multiple Access (OFDMA) systems based on subspace decomposition. We exploit the orthogonality between signal subspace and noise subspace induced by virtual carriers (VCs) and cyclic prefix (CP) and the property of that the exclusive sub-carriers set is assigned to each user to estimate and identify the channels for each user individually. In OFDMA systems, when some users don’t communicate with base station, the sub-carriers of non-active user provide extra redundancy for channel estimate to enhance the accuracy of channel estimation. Furthermore, the sufficient channel identifiability condition is developed.
      Furthermore, a novel scheme, called as virtual carriers recovery (VCR) scheme, is proposed to improve the performance of the subspace-based channel estimation method. It suppresses the noise interference by recovering the VCs to zeros at receiver. The simulation results illustrate that the enhancement of VCR scheme is particularly apparent for the partially loaded OFDMA system at low signal to noise ratio (SNR). In addition, the VCR scheme increases the convergence rate of the subspace-base semi-blind channel estimation.
    Advisory Committee
  • Chin-Liang Wang - chair
  • Ding-Bing Lin - co-chair
  • Char-Dir Chung - co-chair
  • Chih-Peng Li - advisor
  • Tsang-Yi Wang - advisor
  • Files
  • etd-0804108-181143.pdf
  • indicate in-campus access in a year and off_campus not accessible
    Date of Submission 2008-08-04

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