A network node for wireless access operating cell in a cellular network for a licensed or unlicensed frequency band and arranged for serving wireless devices in an unlicensed frequency band is disclosed. The network node is arranged to transmit a discovery reference signal (DRS) comprising a first and a second synchronization signal for enabling the wireless devices to find and measure the cell, wherein the DRS, when the network node operates a primary cell in the unlicensed frequency band, comprises system information, and additional or adapted synchronization signal for enabling the wireless devices to identify the presence of the system information and acquire further cell information. A wireless device for operating with such a network node is also disclosed.