A method, performed in a communication network, of mitigating inter cluster interference, wherein the communication network is configured to coordinate transmissions in a cluster comprising one or more wireless devices (10a, 12a) within two wireless device categories and one or more network nodes, wherein the one or more network nodes in the cluster are transmitting in coordination to the one or more wireless devices (10a, 12a) in the cluster using a plurality of transceiver antennas, wherein one of the two wireless device categories are interference mitigation non-capable wireless devices and one of the two wireless device categories are interference mitigation capable wireless devices, the method comprising: receiving (S2a), during a constrained time interval, for each of the plurality of transceiver antennas in each of the one or more network nodes a first signal comprising pre-defined sounding sequences transmitted by at least one of the one or more wireless devices from a first of the two wireless device categories and sounding channel interference from one or more wireless devices outside the cluster; receiving (S2b), during an unconstrained time interval, for each of the plurality of transceiver antennas in each of the one or more network nodes a second signal comprising pre-defined sounding sequences transmitted by at least one of the one or more wireless devices (10a, 12a) of the cluster from any of the two wireless device categories and sounding channel interference from one or more wireless devices outside the cluster; estimating, from the first signal the sounding channel interference associated with the one or more wireless devices from the first wireless device category; and estimating, from the second signal the sounding channel interference associated with the one or more wireless devices (10a, 12a) from any of the two wireless device categories; and determining downlink precoder weights, for use when transmitting from the transceiver antennas, using the received first signal and second signal, and the estimates of sounding channel interference. receiving (S2a), during a constrained time interval, for each of the plurality of transceiver antennas in each of the one or more network nodes a first signal comprising pre-defined sounding sequences transmitted by at least one of the one or more wireless devices from a first of the two wireless device categories and sounding channel interference from one or more wireless devices outside the cluster; receiving (S2b), during an unconstrained time interval, for each of the plurality of transceiver antennas in each of the one or more network nodes a second signal comprising pre-defined sounding sequences transmitted by at least one of the one or more wireless devices (10a, 12a) of the cluster from any of the two wireless device categories and sounding channel interference from one or more wireless devices outside the cluster; estimating, from the first signal the sounding channel interference associated with the one or more wireless devices from the first wireless device category; and estimating, from the second signal the sounding channel interference associated with the one or more wireless devices (10a, 12a) from any of the two wireless device categories; and determining downlink precoder weights, for use when transmitting from the transceiver antennas, using the received first signal and second signal, and the estimates of sounding channel interference.