DocumentCode :
79185
Title :
A Reduced-State Ungerboeck Type MAP Receiver with Bidirectional Decision Feedback for M-ary Quasi Orthogonal Signaling
Author :
Guvensen, G.M. ; Tanik, Yalcin ; Yilmaz, Ayhan Ozan
Author_Institution :
Dept. of Electr. & Electron. Eng., Middle East Tech. Univ., Ankara, Turkey
Volume :
62
Issue :
2
fYear :
2014
fDate :
Feb-14
Firstpage :
552
Lastpage :
566
Abstract :
In this paper, we propose a generic receiver based on optimum maximum likelihood sequence estimation (MLSE) employing a generalized Ungerboeck metric with significantly reduced complexity for the general class of M-ary quasi orthogonal signaling (MOS) in severe multipath fading channels. First, by using the factor graph (FG) of the obtained generalized Ungerboeck metric for MOS and sum-product algorithm (SPA) framework, a highly efficient reduced state sequence estimation (RSSE) algorithm is proposed that operates on forward and backward directions and is directly applied to unwhitened channel matched filter (CMF) and code matched filter outputs at symbol rate. The proposed structure, generating the a posteriori probabilities (APP) by bidirectional RSSE recursions, are substantiated with symbol rate bidirectional decision feedback (BDF) based on surviving paths in order to eliminate the post- and pre-cursor inter-symbol interference (ISI) as well as multi code interference (MCI) due to the non-ideal properties of the signaling waveforms and multipath channel. It appears as the unification of Ungerboeck type reduced trellis equalization framework for MOS and achieves near-optimum performance especially for channels with large dispersion. Second, we identify a bias term through an error probability analysis which helps us improve the proposed receiver´s performance. Furthermore, a tight approximation for the bit error rate (BER) of the proposed receiver is derived. These analyses lead to significant insight on the selection of system parameters and clearly demonstrate the high performance and efficiency of the proposed scheme by a proper choice of the signaling parameters.
Keywords :
approximation theory; fading channels; intersymbol interference; matched filters; maximum likelihood estimation; probability; APP; BDF; BER; CMF; FG; M-ary quasi orthogonal signaling; MCI; MLSE; MOS; RSSE algorithm; SPA framework; a posteriori probabilities; bidirectional RSSE recursions; bidirectional decision feedback; bit error rate; code matched filter; error probability analysis; factor graph; inter-symbol interference; multi code interference; multipath fading channels; optimum maximum likelihood sequence estimation; reduced state sequence estimation algorithm; reduced-state Ungerboeck type MAP receiver; sum-product algorithm framework; symbol rate bidirectional decision feedback; tight approximation; unwhitened channel matched filter; Complexity theory; Correlation; Interference; Maximum likelihood estimation; Measurement; Modulation; Receivers; Factor Graph (FG); ISI; M-ary quasi orthogonal signaling; MAP Receiver; Reduced State Sequence Estimation (RSSE); Sum-Product Algorithm (SPA); Ungerboeck type MLSE; bias; bidirectional equalization; channel matched filter (CMF); decision feedback; multipath fading;
fLanguage :
English
Journal_Title :
Communications, IEEE Transactions on
Publisher :
ieee
ISSN :
0090-6778
Type :
jour
DOI :
10.1109/TCOMM.2014.011114.130714
Filename :
6725832
Link To Document :
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