This disclosure relates to providing synchronization signal block index signaling in a cellular communication system. A cellular base station may provide synchronization signals according to a periodic pattern, including transmitting one or more synchronization signal bursts each including one or more synchronization signal blocks. A wireless device may detect a synchronization signal block. The wireless device may determine a synchronization signal block index of the detected synchronization signal block. The wireless device may provide an indication of the synchronization signal block index of the detected synchronization signal block to the cellular base station.