Method and apparatus for transmit timing adjustment

Abstract

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.

Description

technical field [0001] Embodiments herein relate to network nodes, user equipment and methods thereof. In particular, embodiments herein relate to adjusting transmission timing of uplink transmissions in a telecommunications system. Background technique [0002] In today's radio communication networks many different technologies are used such as Long Term Evolution (LTE), LTE-Advanced, Wideband Code Division Multiple Access (WCDMA), Global System for Mobile Communications / Enhanced Data Rates for GSM Evolution (GSM / EDGE) , Worldwide Interoperability for Microwave Access (WiMax) or Ultra Mobile Broadband (UMB), to name just a few possible technologies for radio communications. The radio communication network comprises radio base stations providing radio coverage over at least one respective geographical area forming a cell. A cell definition can also contain the frequency band used for transmission, which means that two different cells can cover the same geographical area bu...

AI Technical Summary

Problems solved by technology

[0043] In other words, a large difference between the reference timing of the new timing reference serving cell and the reference timing of the previous timing reference serving cell may lead to sudden and relatively large differences in the transmit timing of uplink transmissions on the serving cell group The change

Such sudden and relatively large changes in transmit timing may cause problems in the reception of uplink transmissions at the network nodes, since e.g. receivers in the network nodes may not be able to keep up with such subframe-by-subframe changes , and thus lead to performance degradation in the network node

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