Applying Frequency-Domain Equalization to Code-Division Multiple Access and Transform-Domain Communications Systems

Abstract

This research examined the theory and application of using discrete multi-tone (DMT) frequency-domain equalization (FEQ) with communications systems that inherently possess null-tones in their respective transmission frequencies. DMT-FEQ relies on null-tones to equalize a non-ideal channel. A Hadamard encoded code division multiple access (CDMA) communications system with up to 32 synchronous users and a transform domain communications system (TDCS) with one user were investigated. Both communications systems were simulated while operating with real channel data corrupted by noise. Simulation results showed that the Hadamard encoded CDMA system worked well with DMT-FEQ only when the transmission signal obeyed DMT-FEQ null-tone conditions in conjunction with a vector estimation method. Simulation results also showed that modifications to TDCS with a conjugate-symmetric phase component in conjunction with a modified spectral mask with consecutive null-tones and forced null-tones provided acceptable results when equalizing with DMT-FEQ.

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Document Details

Document Type
Technical Report
Publication Date
Mar 01, 2008
Accession Number
ADA487015

Entities

People

  • Alfred A. Tamayo Iii

Organizations

  • Air Force Institute of Technology

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Air Force
  • Amplitude Modulation
  • Bandwidth
  • Carrier Frequencies
  • Code Division Multiple Access
  • Communication Systems
  • Demodulators
  • Electrical Engineering
  • Frequency Division Multiple Access
  • Frequency Domain
  • Maximum Likelihood Estimation
  • Modulation
  • Modulators
  • Multiple Access
  • Multiplexing
  • Orthogonal Frequency Division Multiplexing
  • Time Division Multiple Access

Readers

  • Radio communications and signal processing.