Communications device and method

A method of transmitting data to or receiving data from a mobile communications network by a communications device, the mobile communications network including one or more network elements, the one or more network elements forming a plurality of cells of the mobile communications network, each cell being allocated a cell identifier by the mobile communications network and for each cell the one or more network elements provide a wireless access interface for the communications device, the method comprising:

• transmitting signals representing the data from the mobile communications device to the mobile communications network via the wireless access interface;
• receiving signals representing the data at the mobile communications device from the mobile communications network via the wireless access interface, the wireless access interface providing a plurality of communications resource elements across frequency ranges of a first carrier and a second carrier that is not synchronized to the first carrier, and divided in time into a plurality of frames, the one or more network elements transmitting in one or more of the frames a synchronization sequence being one of a set of possible synchronization sequences, each of the synchronization sequences from the set providing an indication of a cell identifier of the cell;
• detecting the synchronization sequence as being one of the predetermined set of synchronization sequences;
• determining a relative temporal location of the synchronization sequence within the frame;
• calculating the cell identifier based on the relative temporal location of the synchronization sequence in combination with the detected synchronization sequence, wherein a value of the calculated cell identifier varies for different relative temporal locations of the synchronization sequence within the frame;
• and
• using the calculated cell identifier, by the communications device, to transmit the data to and/or receive the data from the mobile communications network via the wireless access interface,
• wherein the synchronization sequence includes a first set of synchronization sequences and a second set of synchronization sequences, wherein the first set of synchronization sequences occurs in a same temporal location of a sub-frame of the frame for all cells in the communications network, and wherein the second set of synchronization sequences varies temporally within a sub-frame and between sub-frames of the frame in the communications network,
• wherein the first set of synchronization sequences, which includes a first primary synchronization sequence and a first secondary synchronization sequence, is transmitted via the first carrier, the second set of synchronization sequences, which includes a second primary synchronization sequence and a second secondary synchronization sequence, is transmitted via the second carrier, and the first set of synchronization sequences is transmitted in a same one of sub-frames of the second carrier as the first carrier and a same one of sub-frames of the first carrier for other cells of the mobile communications network,
• wherein both of the first primary synchronization sequence and the first secondary synchronization sequence occur in a same first temporal location of a first sub-frame of the sub-frames and a same second temporal location of a second sub-frame of the sub-frames for multiple frames for all cells in the communications network, the second temporal location being different from the first temporal location, and
• wherein a temporal location of both of the second primary synchronization sequence and the second secondary synchronization sequence varies temporally within the sub-frame and between the sub-frames of multiple frames for different cells in the communications network.