In this paper, we formulate the blind fractionally spaced equalization (FSE) problem as one that minimizes a piecewise linear convex function subject to some linear constraints on the equalizer parameters. We show that this formulation achieves both the interference removal and the carrier phase recovery when the input signal possesses a certain quadrature amplitude modulation (QAM) type symmetry. A fast linear programming implementation is presented to solve the convex minimization problem. Computer simulation results indicate the new linear programming-based FSE is able to accurately equalize channels that are known to be not equalizable by T-spaced (or baud rate) blind equalizers and yields superior performance to other blind FSE methods.
Bibliographical noteFunding Information:
Manuscript received June 16, 1999; revised March 4, 2002. This work was supported by the Natural Sciences and Engineering Research Council of Canada under Grant OPG0090391 and by the Communications Information Technology of Ontario (CITO). The first author was also supported by the Canada Research Chair program. The associate editor coordinating the review of this paper and approving it for publication was Prof. Scott C. Douglas.
- Adaptive systems
- Blind equalization
- Fractionally spaced equalizers
- Intersymbol interference
- Linear programming