Title :
Turbo Equalization for Gray-Coded M-ary QAM with Bit-Level Soft Decisions
Author :
Lin, D.D. ; Teng Joon Lim
Author_Institution :
Univ. of Toronto, Toronto
Abstract :
This paper investigates the soft-in soft-out (SISO) equalization of multilevel QAM symbols in coded inter-symbol interference (ISI) channels. Unlike the conventional approach of performing equalization at the symbol level, the proposed scheme targets the channel bits directly. This solution can be seen to belong to a family of SISO detection schemes which we call Bit-Level Equalization and Soft Detection (BLESD), stemming from the minimization of variational free energy given different postulates about the prior and posterior distributions of the channel bits. Simulation results demonstrate that the bit-level approach outperforms the symbol-level alternative in terms of error rate in the Porat-Friedlander channel.
Keywords :
Gray codes; intersymbol interference; quadrature amplitude modulation; turbo codes; Porat-Friedlander channel; bit-level equalization and soft detection; bit-level soft decisions; coded inter-symbol interference channels; gray-coded M-ary QAM; soft-in soft-out equalization; turbo equalization; Decision feedback equalizers; Detectors; Educational institutions; Error analysis; Error correction; Intersymbol interference; Iterative decoding; MIMO; Quadrature amplitude modulation; Strontium;
Conference_Titel :
Information Theory, 2007. ISIT 2007. IEEE International Symposium on
Conference_Location :
Nice
Print_ISBN :
978-1-4244-1397-3
DOI :
10.1109/ISIT.2007.4557144