The present invention provides a method of determining a transmission power for device to device, D2D, transmissions between a first user equipment device and a second user equipment device using transmission resources being used for transmissions to a cellular network entity by a third user equipment device, the method comprising determining a measure of a path loss between the cellular network entity and the first user equipment device, and using the measure of the path loss to determine a maximum transmission power such that the D2D transmissions are received at the cellular network entity with a signal level around or below a noise level.