Network Node, User Equipment and Methods Therein for Adjusting the Transmit Timing of Uplink Transmissions

A user equipment adapted to adjust a transmit timing of uplink transmissions to a network node in a telecommunications system, the user equipment comprising:

• processing circuitry configured to:
• identify a second timing reference serving cell in a group of serving cells sharing a common timing advance value, the second timing reference serving cell being different from a first timing reference serving cell currently being used as the timing reference serving cell defining a common uplink transmit timing for uplink transmission by each of the aggregated serving cells in the group of serving cells;
• responsive to identifying the second timing reference serving cell, change the common uplink transmit timing responsive to a reception timing of a downlink transmission received at the user equipment from the second timing reference serving cell by apply an incremental adjustment to the common uplink transmit timing, wherein said applying the incremental adjustment comprises gradually applying two or more adjustments to the common uplink transmit timing for uplink transmissions for each of the aggregated serving cells in the group of serving cells comprising the first and second timing reference serving cells.

A method, in a network node, for determining information for adjusting a transmit timing of uplink transmissions of a user equipment in a telecommunications system, the method comprising:

• determining adjustment information for an incremental adjustment of a common uplink transmit timing for uplink transmissions to serving cells in a group of serving cells sharing a common timing advance value, the incremental adjustment comprising a change from a first timing reference serving cell for the group of serving cells to a second timing reference serving cell different from the first timing reference serving cell on which a timing reference is currently based, wherein the incremental adjustment comprises two or more adjustments gradually applied to the common uplink transmit timing for uplink transmissions for each of the aggregated serving cells in the group of serving cells comprising the first and second timing reference serving cells;
• and
• transmitting the adjustment information to the user equipment.

A network node for determining information for adjusting the transmit timing of uplink transmissions of a user equipment in a telecommunications system, the network node comprising:

• processing circuitry configured to determine adjustment information for an incremental adjustment of a common uplink transmit timing for uplink transmissions to serving cells in a group of serving cells sharing a common timing advance value, the incremental adjustment comprising a change from a first timing reference serving cell for the group of serving cells to a second timing reference serving cell different from the first timing reference serving cell on which a timing reference is currently based, wherein the incremental adjustment comprises two or more adjustments gradually applied to the common uplink transmit timing for uplink transmissions for each of the aggregated serving cells in the group of serving cells comprising the first and second timing reference serving cells;
• and
• radio circuitry configured to transmit the adjustment information to the user equipment.