A User Equipment, UE, comprising: a processor; memory in electronic communication with the processor; instructions stored in the memory, the instructions being executable to: determine multiple groups of one or more serving cells for wireless communication; and adjust uplink transmission timing of one or more serving cells of each group so that all serving cells in a group have the same uplink transmission timing, wherein the multiple groups consist of a primary cell group containing at least a primary cell and at least one non-primary cell group not containing the primary cell but containing at least one secondary cell and the User Equipment adjusts timing so that: timing of transmission for a physical uplink shared channel and/or a sounding reference signal of at least one of secondary cells in the primary cell group being the same as the primary cell if the primary cell group contains said at least one of the secondary cells; and timing of transmission for a physical uplink shared channel and/or a sounding reference signal of all secondary cells in each of said at least one non-primary cell group being same for the all secondary cells, characterized in that a path loss reference for a secondary cell in the primary cell group is selected from the primary cell or the secondary cell and the primary cell is not used as a path loss reference for a secondary cell in said at least one non-primary cell group. a processor; memory in electronic communication with the processor; instructions stored in the memory, the instructions being executable to: determine multiple groups of one or more serving cells for wireless communication; and adjust uplink transmission timing of one or more serving cells of each group so that all serving cells in a group have the same uplink transmission timing, determine multiple groups of one or more serving cells for wireless communication; and adjust uplink transmission timing of one or more serving cells of each group so that all serving cells in a group have the same uplink transmission timing, wherein the multiple groups consist of a primary cell group containing at least a primary cell and at least one non-primary cell group not containing the primary cell but containing at least one secondary cell and the User Equipment adjusts timing so that: timing of transmission for a physical uplink shared channel and/or a sounding reference signal of at least one of secondary cells in the primary cell group being the same as the primary cell if the primary cell group contains said at least one of the secondary cells; and timing of transmission for a physical uplink shared channel and/or a sounding reference signal of all secondary cells in each of said at least one non-primary cell group being same for the all secondary cells, characterized in that timing of transmission for a physical uplink shared channel and/or a sounding reference signal of at least one of secondary cells in the primary cell group being the same as the primary cell if the primary cell group contains said at least one of the secondary cells; and timing of transmission for a physical uplink shared channel and/or a sounding reference signal of all secondary cells in each of said at least one non-primary cell group being same for the all secondary cells, characterized in that a path loss reference for a secondary cell in the primary cell group is selected from the primary cell or the secondary cell and the primary cell is not used as a path loss reference for a secondary cell in said at least one non-primary cell group.