Technology for an apparatus of a user equipment (UE) configured to select spectrum resources in a vehicle to vehicle (V2V) communication system is disclosed. It relies on the established mechanisms for device-todevice, D2D direct mode communication well-known in the context of Proximity Services in a 3GPP LTE communications system. The UE can calculate a received energy in a physical sidelink shared channel (PSSCH) over a sensing period for a portion of one or more sub-channels over selected subframes in a resource pool, by means of measurements of Received Signal Strength Indication, RSSI, of other D2D sidelink channel communications. The UE can identify the one or more sub-channels over the selected subframes that has a measured energy level greater than a threshold value to determine a channel congestion fraction (CCF) comprising a fraction of the resources that exceed the threshold value, reflecting a resource utilization. The UE can send the channel congestion fraction (CCF) to an upper layer of the UE to enable resource reselection for the UE based on the fraction of the resources that exceed the threshold value. The configuration of D2D retransmission parameters is in particular addressed, according to the measured congestion or interference. The UE may as well transmit the measured CCF to a base station evolved node B, eNB, which may accordingly reconfigure the UE's sidelink channel communication transmission parameters.