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{{Short description|Signal processing technique}}
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{{Modulation techniques}}
'''Hierarchical modulation''', also called '''layered modulation''', is one of the [[signal processing]] techniques for [[multiplexing]] and [[modulation|modulating]] multiple data streams into one single symbol stream, where base-layer symbols and enhancement-layer symbols are synchronously
Hierarchical modulation is particularly used to mitigate the [[cliff effect]] in [[digital television]] broadcast, particularly [[mobile TV]], by providing a (lower quality) fallback signal in case of weak signals, allowing [[graceful degradation]] instead of complete signal loss. It has been widely proven and included in various standards, such as [[DVB-T]], [[MediaFLO]], UMB ([[Ultra Mobile Broadband]], a new 3.5th generation mobile network standard developed by 3GPP2), and is under study for [[DVB-H]].
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