A network node configured to control transmissions in a first wireless network, the first wireless network transmissions occurring in a frequency band used for contention-based transmissions in a second wireless network, the network node comprising circuitry containing instructions which, when executed, cause the network node to:
- after a first wireless network transmission in the first wireless network, determine a start time of a contention-based transmission in the second wireless network;
- estimate a number of active wireless devices perating in the second wireless network based on the start time;
- and
- adjust a transmission time duration for a subsequent first wireless network transmission based on the number of active wireless devices estimated.