Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a base station (BS) may process, for a plurality of search space (SS) set occasions, a plurality of narrowband (NB) demodulation reference signals (DMRSs) using a common precoder in a common resource element group (REG). The BS may transmit the plurality of NB DMRSs within a union of REGs of each physical downlink control channel for each aggregation level configured for the plurality of SS set occasions. Numerous other aspects are provided.