Design of robust adaptive equalizers for digital radio systems
M. Bellec, Hikmet Sari · 2003
The issue of adaptive equalizer behavior during the events of carrier synchronism loss in digital microwave radio systems is addressed. It is shown that, in the case of a QPSK system, conventional algorithms are very sensitive to carrier synchronism loss, and that a simple modification considerably improves their stability. Next, a 64-QAM system is considered, and the conventional zero-forcing algorithm (ZFA) and the maximum-level error algorithm (MLEA) are examined along with a new variant of the ZFA. A comparative study is made between the algorithms in terms of their self-noise, stability, and tracking speed. The results indicate that the proposed algorithm significantly improves the system robustness during loss of synchronism.>