This disclosure provides systems, methods and apparatus for wireless communications in narrowband frequency bands using frequency hopping. In some implementations, a base station (BS) groups a plurality of hopping channels of a frequency hopping pattern into a number of groups based on a bandwidth part (BWP) hopping frequency of each hopping channel of the frequency hopping pattern. The BS transmits indications of the frequency hopping pattern and the grouping of hopping channels to user equipments (UEs). The BS transmits a channel state information reference signal (CSI-RS) on a first hopping channel, and receives channel state information (CSI) of the first hopping channel from one or more of the UEs. In some other implementations, a UE receives indications of the frequency hopping pattern and hopping channel groups, and determines CSI of the first hopping channel based on the received CSI-RS. The UE may transmit the CSI to the BS.