Methods, systems, and devices for wireless communications are described. A wireless device (e.g., a user equipment and/or base station) may operate in a first mode in a wireless network over a radio frequency spectrum band. The wireless device may receive a signal indicating that a value of the radio frequency spectrum band has satisfied a threshold value. The wireless device may switch, based at least in part on the signal indicating that the value has satisfied the threshold value, from the first mode to a second mode for wireless communications in the wireless network, wherein a first length of a first synchronization signal block associated with the first mode is shorter than a second length of a second synchronization signal block associated with the second mode.