Unlicensed cell downlink signal synchronization

A wireless device comprising:

• one or more processors;
• and
• memory storing instructions that, when executed by the one or more processors, cause the wireless device to:
• receive configuration parameters of a timing advance group (TAG) comprising a first unlicensed cell and a second unlicensed cell;
• receive, via the first unlicensed cell of the TAG, a first signal comprising a first downlink synchronization signal;
• receive, via the second unlicensed cell of the TAG, a second signal comprising a second downlink synchronization signal;
• synchronize a first downlink signal timing with the first unlicensed cell based on both of the first signal received via the first unlicensed cell of the TAG and the second signal received via the second unlicensed cell of the TAG;
• and
• synchronize a second downlink signal timing with the second unlicensed cell based on both of the first signal received via the first unlicensed cell of the TAG and the second signal received via the second unlicensed cell of the TAG.