A network node, comprising: a processing unit configured to: group a plurality of UEs (220-1, 220-2, 220-3, 220-4) into at least a first UE group and a second UE group; assign a mutually orthogonal pilot sequence to each UE (220-1, 220-2) comprised in the first UE group; assign a mutually orthogonal pilot sequence to each UE (220-3, 220-4) comprised in the second UE group; and assign a resource-offset to the UEs (220-1, 220-2, 220-3, 220-4) comprised in each UE group (260, 270), by which each UE (220-1, 220-2, 220-3, 220-4) is allowed to start its transmission sub-frame in its Transmission Time Interval, TTI, wherein the resource-offset comprises a time-offset or a frequency-offset; and a transmitter configured to transmit the pilot sequences and the resource-offset to UEs (220-1, 220-2, 220-3, 220-4); wherein the processing unit is further configured to assign the resource-offset such that the pilot sequences of the UEs (220-1, 220-2) in the first UE group are not interfered by the pilot sequences of the UEs (220-3, 220-4) in the second UE group; wherein the processing unit is further configured to instruct at least one UE (220-1, 220-2, 220-3, 220-4) to adjust transmission power, based on at least one of: the channel estimation of each UE group (260, 270) and the interference among the UE groups (260, 270). a processing unit configured to: group a plurality of UEs (220-1, 220-2, 220-3, 220-4) into at least a first UE group and a second UE group; assign a mutually orthogonal pilot sequence to each UE (220-1, 220-2) comprised in the first UE group; assign a mutually orthogonal pilot sequence to each UE (220-3, 220-4) comprised in the second UE group; and assign a resource-offset to the UEs (220-1, 220-2, 220-3, 220-4) comprised in each UE group (260, 270), by which each UE (220-1, 220-2, 220-3, 220-4) is allowed to start its transmission sub-frame in its Transmission Time Interval, TTI, wherein the resource-offset comprises a time-offset or a frequency-offset; and group a plurality of UEs (220-1, 220-2, 220-3, 220-4) into at least a first UE group and a second UE group; assign a mutually orthogonal pilot sequence to each UE (220-1, 220-2) comprised in the first UE group; assign a mutually orthogonal pilot sequence to each UE (220-3, 220-4) comprised in the second UE group; and assign a resource-offset to the UEs (220-1, 220-2, 220-3, 220-4) comprised in each UE group (260, 270), by which each UE (220-1, 220-2, 220-3, 220-4) is allowed to start its transmission sub-frame in its Transmission Time Interval, TTI, wherein the resource-offset comprises a time-offset or a frequency-offset; and a transmitter configured to transmit the pilot sequences and the resource-offset to UEs (220-1, 220-2, 220-3, 220-4); wherein the processing unit is further configured to assign the resource-offset such that the pilot sequences of the UEs (220-1, 220-2) in the first UE group are not interfered by the pilot sequences of the UEs (220-3, 220-4) in the second UE group; wherein the processing unit is further configured to instruct at least one UE (220-1, 220-2, 220-3, 220-4) to adjust transmission power, based on at least one of: the channel estimation of each UE group (260, 270) and the interference among the UE groups (260, 270).