Blind Equalization of COFDM Systems Based on the Minimization of a Quadratic Criterion

The COFDM concept has recently been applied to the design of DFT-based digital modulations for use over frequency selective channels. The cyclic convolution property of the DFT enables a low complexity equalization scheme at the expense of bandwidth efficiency since a “guard time” is required. Moreover this technique is very specific to DFT-based OFDM systems. As digital modulations generate continuous signals after baseband level digital filtering, non-critical sampling is recommended, that is, some zero symbols must be appended to the block of symbols to be modulated. As shown in [10], minimizing a quadratic criterion based on the subband components of the received signal that should be null is sufficient to perform (blind) equalization. Therefore less channel capacity is lost since neither a guard time nor reference symbols are required. The performance of a linear equalizer using this criterion is studied here for COFDM systems with 64-QAM subcarrier modulation.

Published

1996-10

Content type

Original Research

DOI

10.5594/M001263

ISBN

978-1-61482-947-8