The present invention relates to methods and arrangements for providing a more flexible configuration of SRS transmission. This is achieved by dynamically triggering a mobile terminal to transmit SRS. Thus, embodiments of the invention allow dynamically trigged SRS in any uplink subframe, even without necessarily reserving resources semi-statically on cell level. This is done by signaling to the terminal whether the mobile terminal should leave the predefined uplink symbol empty for sounding reference signals or use it for data transmission. In case a terminal leaves the last symbol empty for sounding reference signals, there are two possibilities, either the UE shall transmit one or several reference signals from one or several antennas, or the terminal shall leave the last symbol blank since another terminal may be using the resource for sounding. Accordingly, in a specific embodiment, there are at least three different messages that can be conveyed to the terminal: use the predefined uplink symbol for data, leave it blank or use it for sounding reference signals.