Digital Radio Mondiale (DRM) is the universally, openly standardized digital broadcasting system for all frequencies\nincluding LW, MW, and SW as well as VHF bands. Alongside providing high audio quality to listeners, DRM satisfies\ntechnological requirements posed by broadcasters, manufacturers and regulatory authorities and thus bears a great\npotential for the future of global radio. One of the key issues here concerns green broadcasting. Facing the need for\nhigh-power transmitters to cover wide areas, there is room for improvement concerning the power efficiency of\nDRM-transmitters. A major drawback of DRM is its high peak-to-average power ratio (PAPR) due to the applied\ntransmission technology based on Orthogonal Frequency Division Multiplexing (OFDM), which results in\nnon-linearities in the emitted signal, low power efficiency, and high costs of transmitters. To overcome this, numerous\nschemes have been investigated for reducing PAPR in OFDM systems. In this paper, we review and analyze various\ntechnologies to reduce PAPR providing that the technical feasibility and DRM-specific system architecture and edge\nconditions regarding the system performance in terms of modulation error rate, compliance with frequency mask,\nand synchronization efficiency are ensured. All evaluations are carried out with I/Q signals which are monitored in real\noperation to present the actual performance of proposed PAPR techniques. Subsequently, the capability of the best\napproach is evaluated via measurements on a DRM test platform, where achieved transmit power gain of 10 dB is\nshown. According to our evaluation results, PAPR reduction schemes based on active constellation extension\nfollowed by a filter prove to be promising towards practical realization of power-efficient transmitters.
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