METHOD AND APPARATUS FOR TRANSMIT TIMING ADJUSTMENT

摘要

A method in a user equipment (121) for adjusting a transmit timing of uplink transmissions to a network node (110) in a telecommunications system (100) is provided. The user equipment (121) is configurable with more than one aggregated serving cells. The more than one aggregated serving cells are divided into one or more groups of serving cells based on a timing advance value of each of the aggregated serving cells. The one or more groups of serving cells each comprises a timing reference serving cell. The reception timing of a downlink transmission from a timing reference serving cell is used as a timing reference for the transmit timing of uplink transmissions for the serving cells in the group of serving cells comprising the timing reference serving cell, respectively. The user equipment (121) determines a change to a second timing reference serving cell in a group of serving cells, which second timing reference serving cell is different from a first timing reference serving cell currently being used as the timing reference serving cell for the group of serving cells. Then, the user equipment (121) applies an incremental adjustment of the transmit timing of uplink transmissions for the serving cells in the group of serving cells with respect to a timing reference based on the reception timing of a downlink transmission from the second timing reference serving cell in the user equipment (121). A user equipment, a method in network node and a network node are also provided.