A method by a first base station of coordinating access to a shared communication medium in a wireless communications system, comprising: determining that the shared communication medium is free; transmitting a grant indicating a first set of SRS resources or triggering a first SRS transmission when the first set of SRS resources is semi-statically configured, for a first user equipment, UE, associated with the first base station during a first medium access slot (200-a) of a plurality of medium access slots before a data burst of a transmission opportunity, TxOP, (420; 530; 620; 740; 850); and receiving , on the first set of SRS resources during an uplink portion of the first medium access slot (200-a) on the shared communication medium, a first response message from the first UE including at least one of a first SRS from the first UE or a clear to send CTS message, the method characterized by further comprising: receiving , during at least a second medium access slot (200-b) of the plurality of medium access slots before the data burst of the TxOP, a transmission from the first UE of the first response message including the first SRS on the first set of SRS resources; and receiving during the second medium access slot (200-b), a second response message from a second UE associated with a second base station, wherein the second response message includes a second SRS that uses different resources than the transmission from the first UE . determining that the shared communication medium is free; transmitting a grant indicating a first set of SRS resources or triggering a first SRS transmission when the first set of SRS resources is semi-statically configured, for a first user equipment, UE, associated with the first base station during a first medium access slot (200-a) of a plurality of medium access slots before a data burst of a transmission opportunity, TxOP, (420; 530; 620; 740; 850); and receiving , on the first set of SRS resources during an uplink portion of the first medium access slot (200-a) on the shared communication medium, a first response message from the first UE including at least one of a first SRS from the first UE or a clear to send CTS message, the method characterized by further comprising: receiving , during at least a second medium access slot (200-b) of the plurality of medium access slots before the data burst of the TxOP, a transmission from the first UE of the first response message including the first SRS on the first set of SRS resources; and receiving during the second medium access slot (200-b), a second response message from a second UE associated with a second base station, wherein the second response message includes a second SRS that uses different resources than the transmission from the first UE . receiving , during at least a second medium access slot (200-b) of the plurality of medium access slots before the data burst of the TxOP, a transmission from the first UE of the first response message including the first SRS on the first set of SRS resources; and receiving during the second medium access slot (200-b), a second response message from a second UE associated with a second base station, wherein the second response message includes a second SRS that uses different resources than the transmission from the first UE . <EOS>