Transmitting synchronisation signals on multiple carriers

A base station for transmitting synchronisation signals on a plurality of carriers, wherein the base station comprises processing circuitry and a machine-readable medium storing instructions which, when executed by the processing circuitry, cause the base station to:

• apply a time shift to at least part of a first synchronisation signal to be sent by the base station on a first carrier of the plurality of carriers such that the at least part of the first synchronisation signal is offset in time from a second synchronisation signal to be sent on a second carrier of the plurality of carriers;
• combine signals for the plurality of carriers, including the first and second synchronisation signals, to form a combined signal;
• amplify the combined signal using a power amplifier;
• and
• transmit the amplified combined signal, wherein the time shift applied to the at least part of the first synchronisation signal is determined based on a physical cell identifier NPCI associated with the first carrier, and wherein applying a time shift comprises applying respective time shifts to at least parts of the synchronisation signals for the plurality of carriers, such that the parts of any two synchronisation signals of the plurality of carriers comprising a same sequence are offset in time from each other, wherein the amount of time shift applied is smaller than the time values used to allocate time resources, wherein the base station is configured to repeat sequences used for synchronisation signals every n carriers and a time offset for the first carrier is determined based on n.