There is proposed a mechanism for power saving procedures to be conducted in transmission network nodes, such as base stations or the like, in a heterogeneous network environment. A transmission node is set to operate in a sensor mode for conducting traffic monitoring when an operation mode of the transmission node is an inactive state. Information necessary for the traffic monitoring by the transmission node based on detection of random access channel (RACH) signals of neighboring cells is provided. On the basis of results of the monitoring of RACHs of the neighboring cells, it is determined whether the inactive transmission node is to be reactivated.