A communications device transmits/receives data from a mobile communications network including one or more network elements forming plural cells. Each cell is allocated a cell identifier. For each cell the network elements provide a wireless access interface providing plural communications resource elements across a frequency range of a first carrier, and divided in time into plural frames. The one or more network elements transmit in one or more of the frames a synchronization sequence, each synchronization sequence providing an indication of a cell identifier. A controller calculates an estimate of a cell identifier from the detected synchronization sequence, and uses the cell identifier to transmit/receive the data to/from the mobile communications network via the wireless access interface. A relative temporal location of the synchronization sequence within the frame provides the communications device with an indication of the cell identifier of the cell.