Blind carrier recovery for circular QAM using nonlinear least-squares estimation

Timothy Duryea, Ilkay Sari, Erchin Serpedin

Research output: Contribution to journalArticle

3 Citations (Scopus)


In this work, a family of blind feedforward nonlinear least-squares (NLS) estimators for joint estimation of the carrier phase and frequency offset of circular quadrature amplitude modulated (QAM) transmissions is introduced. Well-known synchronization techniques are adapted for the circular QAM schemes, and a constellation-dependent optimal matched nonlinear estimator is derived to minimize the asymptotic variance. A computationally efficient approximation to the optimal nonlinearity is introduced and its performance assessed. Finally, computer simulations for various circular QAM transmissions are carried out to show that the proposed estimation technique is competitive with conventional monomial estimators. From the simulation results, conclusions are drawn about selecting the best synchronization method for implementation in actual communication systems.

Original languageEnglish
Pages (from-to)358-368
Number of pages11
JournalDigital Signal Processing: A Review Journal
Issue number4
Publication statusPublished - Jul 2006
Externally publishedYes



  • Blind synchronization
  • Carrier phase
  • Carrier synchronization
  • Circular QAM
  • Frequency offset
  • Nonlinear least-squares estimator

ASJC Scopus subject areas

  • Signal Processing
  • Electrical and Electronic Engineering

Cite this