A wireless device initializes a candidate resource set. The candidate resource set comprises candidate resources in a selection window. The wireless device receives a second sidelink transmission. The second sidelink transmission comprises sidelink control information (SCI). The SCI indicates first resources during the selection window. The SCI indicates a priority of the second sidelink transmission. The priority is used for excluding the first resources from the candidate resource set. The wireless device excludes the first resources from the candidate resource set based on the priority being higher than a first priority threshold. The wireless device selects second resources from the candidate resource set based on the excluding of the first resources from the candidate resource set. The wireless device transmits a first sidelink transmission via the second resources.