Title :
A generalized BCJR algorithm and its use in turbo synchronization
Author :
Gunther, Jacob H. ; Keller, David ; Moon, Todd K.
Author_Institution :
Dept. of Electr. & Comput. Eng., Utah State Univ., Logan, UT, USA
Abstract :
A generalization of the BCJR algorithm is derived to compute joint posterior probabilities of arbitrary sets of symbols given received data. A special case of the new algorithm that computes pairwise joint probabilities is used to evaluate the second order statistics needed for EM estimation of carrier phase and symbol timing offsets in a digitally modulated waveform. This EM estimator is integrated into a turbo synchronization loop in which soft information is exchanged between the generalized BCJR algorithm (the synchronizer) and an LDPC decoder.
Keywords :
modulation; parameter estimation; parity check codes; phase estimation; probability; synchronisation; turbo codes; EM estimation; EM estimator; LDPC decoder; carrier phase estimation; digitally modulated waveform; generalized BCJR algorithm; joint posterior probabilities; pairwise joint probabilities; second order statistics; soft information; symbol timing offsets; synchronizer; turbo synchronization loop; Digital modulation; Equations; Intersymbol interference; Iterative decoding; Maximum likelihood decoding; Parity check codes; Phase estimation; Probability; Pulse modulation; Timing;
Conference_Titel :
Acoustics, Speech, and Signal Processing, 2005. Proceedings. (ICASSP '05). IEEE International Conference on
Print_ISBN :
0-7803-8874-7
DOI :
10.1109/ICASSP.2005.1415840
