Title :
Reduced-complexity MAP equalizer for dispersive channels
Author :
Lopez, Michael J. ; Zangi, Kambiz ; Jung-Fu Chen
Author_Institution :
MIT, Cambridge, MA, USA
Abstract :
We present a computationally efficient soft-output equalizer for communication over dispersive channels. The proposed equalizer has a forward and backward recursion structure similar to the classic BCJR MAP algorithm, but its complexity is reduced by constructing a reduced-state trellis, as in the decision feedback sequence estimator (DFSE). We are able to achieve consistent state definitions by running the backward pass on the same trellis as the forward pass. The performance of this reduced-complexity equalizer is evaluated within an iterative receiver in which the intersymbol interference (ISI) channel and channel code are treated as serially concatenated codes. The EDGE air interface is used as an illustrative example, for which we are able to reduce the number of states from 4096 to 8
Keywords :
channel coding; computational complexity; concatenated codes; dispersive channels; equalisers; intersymbol interference; network interfaces; radio receivers; BCJR MAP algorithm; EDGE air interface; ISI channel; backward pass; backward recursion structure; channel code; computationally efficient soft-output equalizer; decision feedback sequence estimator; dispersive channels; forward pass; forward recursion structure; intersymbol interference; iterative receiver; reduced-complexity MAP equalizer; reduced-complexity equalizer; reduced-state trellis; serially concatenated codes; state definitions; Concatenated codes; Convolutional codes; Dispersion; Equalizers; Feedback; Intersymbol interference; Iterative decoding; Maximum likelihood decoding; Maximum likelihood estimation; Recursive estimation;
Conference_Titel :
Vehicular Technology Conference, 2000. IEEE-VTS Fall VTC 2000. 52nd
Conference_Location :
Boston, MA
Print_ISBN :
0-7803-6507-0
DOI :
10.1109/VETECF.2000.886321
