Various communication systems may benefit from appropriate handling of uplink communications. For example, certain wireless communication systems may benefit from an uplink coverage extension for unlicensed band operation. A method can include configuring a first interlace having a first starting physical resource block. The method can also include configuring a second interlace having a second starting physical resource block offset from the first physical resource block. The method can further include transmitting or receiving a signal based on a combination of the first interlace and the second interlace. The combination can include at least one cluster but less than two clusters in each measurement interval.