DocumentCode :
2657093
Title :
Prefiltered Low Complexity Tree Detection for Frequency Selective Fading Channels
Author :
Detert, Thorben
Author_Institution :
Rohde & Schwarz, Munich
fYear :
2007
fDate :
22-25 April 2007
Firstpage :
2364
Lastpage :
2368
Abstract :
We target M-ary data sequence estimation over time-variant frequency selective fading channels. Recently, we proposed a low complexity breadth first tree detector, termed improved M-algorithm (IMA). Unlike the M-algorithm (MA), it takes the whole energy of the received symbol of the current step into account when choosing survivors. Unknown future symbols overlap with postcursors of the current symbol and are modelled as additive Gaussian noise in the metric. Thus, unlike the standard MA, IMA works well without an energy compacting front end prefilter (FEP) even in frequency-selective channels, whereas a FEP is crucial for ordinary reduced state sequence estimators such as the delayed decision feedback sequence estimator (DDFSE) and reduced state sequence estimator (RSSE). However, although not explicitly needed, we show that the complexity of IMA can be reduced even more applying a FEP, because the first channel tap has increased energy, and the effective channel would be even shorter, so that the influence of future symbols on the postcursors is smaller, enabling the tree detector to chose the paths through the tree more precisely. We propose to make use of the cepstrum to compute the FEP via a minimum phase target impulse response. We use the GSM/EDGE modulation format here, in order to enable other researchers to compare their results. Simulation results indicate that for the given application, IMA is superior to RSSE with similar complexity.
Keywords :
Gaussian noise; cellular radio; fading channels; filtering theory; trees (mathematics); EDGE; GSM; M-ary data sequence estimation; additive Gaussian noise; delayed decision feedback sequence estimator; improved M-algorithm; minimum phase target impulse response; modulation format; prefiltered low complexity tree detection; reduced state sequence estimator; state sequence estimators; time-variant frequency selective fading channels; Additive noise; Cepstrum; Delay estimation; Detectors; Fading; Frequency estimation; GSM; Gaussian noise; State estimation; State feedback;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Vehicular Technology Conference, 2007. VTC2007-Spring. IEEE 65th
Conference_Location :
Dublin
ISSN :
1550-2252
Print_ISBN :
1-4244-0266-2
Type :
conf
DOI :
10.1109/VETECS.2007.488
Filename :
4212916
Link To Document :
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