According to an example aspect of the present invention, there is provided a method, including receiving, by a wireless device of a first wireless network, a control request frame from a second access node of a second wireless network, the control request frame including at least a number of nulls for the wireless device. The wireless device selects a subset of antenna elements, wherein the number of antenna elements is in accordance with the number of nulls for the wireless device, and the antenna elements are selected based on reception powers of antenna elements of at least a frame from a first access node of the first wireless network and/or the second access node of the second wireless network. The wireless device transmits a control response frame with the selected antenna elements, and a data frame to the first access node with the selected antenna elements.