Network node for a wireless communication system, the network node comprising: a transceiver configured to: receive a plurality of reference signals (502a, 502b,..., 502n) associated with a plurality of user devices (300a, 300b,..., 300n), a processor configured to: group the plurality of user devices (300a, 300b,..., 300n) into at least one group of user devices based on the plurality of received reference signals (502a, 502b,..., 502n), assign radio resources for grant-free data transmission to the group of user devices,determine a first control message for at least one user device of the group of user devices, wherein the first control message indicates the assigned radio resources, wherein the transceiver is configured to: transmit the first control message to the user device, the processor is further configured to: determine at least one Modulation and Coding Scheme, MCS, based on the plurality of received reference signals (502a, 502b,..., 502n), wherein the transceiver is configured to: transmit a second control message to the user device, wherein the second control message indicates the MCS to be used by the user device in the grant-free data transmission, wherein the second control message further indicates a MCS update instruction instructing the user device to update the MCS for the grant-free data transmission, the processor further configured to: compute a receiver filter for the group of user devices based on the plurality of received reference signals (502a, 502b,..., 502n) and the assigned radio resources, wherein the transceiver is configured to: receive a plurality of grant-free data transmissions from user devices in the group of user devices in the assigned radio resources, wherein the processor is configured to: separate the grant-free data transmissions from the user devices in the group of user devices based on the computed receiver filter. a transceiver configured to: receive a plurality of reference signals (502a, 502b,..., 502n) associated with a plurality of user devices (300a, 300b,..., 300n), a processor configured to: group the plurality of user devices (300a, 300b,..., 300n) into at least one group of user devices based on the plurality of received reference signals (502a, 502b,..., 502n), assign radio resources for grant-free data transmission to the group of user devices,determine a first control message for at least one user device of the group of user devices, wherein the first control message indicates the assigned radio resources, wherein the transceiver is configured to: transmit the first control message to the user device, the processor is further configured to: determine at least one Modulation and Coding Scheme, MCS, based on the plurality of received reference signals (502a, 502b,..., 502n), group the plurality of user devices (300a, 300b,..., 300n) into at least one group of user devices based on the plurality of received reference signals (502a, 502b,..., 502n), assign radio resources for grant-free data transmission to the group of user devices,determine a first control message for at least one user device of the group of user devices, wherein the first control message indicates the assigned radio resources, wherein the transceiver is configured to: transmit the first control message to the user device, the processor is further configured to: determine at least one Modulation and Coding Scheme, MCS, based on the plurality of received reference signals (502a, 502b,..., 502n), transmit the first control message to the user device, the processor is further configured to: determine at least one Modulation and Coding Scheme, MCS, based on the plurality of received reference signals (502a, 502b,..., 502n), wherein the transceiver is configured to: transmit a second control message to the user device, wherein the second control message indicates the MCS to be used by the user device in the grant-free data transmission, wherein the second control message further indicates a MCS update instruction instructing the user device to update the MCS for the grant-free data transmission, the processor further configured to: compute a receiver filter for the group of user devices based on the plurality of received reference signals (502a, 502b,..., 502n) and the assigned radio resources, wherein the transceiver is configured to: receive a plurality of grant-free data transmissions from user devices in the group of user devices in the assigned radio resources, transmit a second control message to the user device, wherein the second control message indicates the MCS to be used by the user device in the grant-free data transmission, wherein the second control message further indicates a MCS update instruction instructing the user device to update the MCS for the grant-free data transmission, the processor further configured to: compute a receiver filter for the group of user devices based on the plurality of received reference signals (502a, 502b,..., 502n) and the assigned radio resources, wherein the transceiver is configured to: receive a plurality of grant-free data transmissions from user devices in the group of user devices in the assigned radio resources, wherein the processor is configured to: separate the grant-free data transmissions from the user devices in the group of user devices based on the computed receiver filter.