Reduction of Out-of-Band Radiation in OFDM Based DRM Simulcast Systems

The simulcast transmission of the DRM and AM is an important approach during the interim from the analogue AM to digital AM broadcasting below 30 MHz. The reduction of out-of-band (OOB) radiation of OFDM signals in simulcast systems is one of the essential issues. In this paper, we introduce the concept of the cancellation carriers (CCs) which suppress the sidelobes of the OFDM signal by inserting well-defined subcarriers at the borders of the OFDM spectrum. In order to satisfy the demand of the simulcast system, we proposed limited-CCs method in which we occupy the subcarriers originally used for data transmission instead of inserting new subcarriers. Simulation results show that by the proposed technique the OOB power can be decreased by about 15 dB at the cost of a slight loss of data rate