cket arrival 836 Chapter 7 occurs. The scheduling request mask per traffic type is not supported for V2X sidelink com- munication. The serving cell can provide synchronization configuration for the V2X side- link carrier. In this case, the UE follows the synchronization configuration received from serving cell. If no cell is detected on the carrier used for V2X sidelink communication and the UE does not receive synchronization configuration from serving cell, the UE follows preconfigured synchronization procedure. There are three possible synchronization nodes; that is, eNB, UE, and GNSS. In case GNSS is configured as synchronization source, the UE utilizes the universal time and the (pre)configured direct frame number (DFN) offset to cal- culate DFN and subframe number. If the eNB timing is configured as synchronization refer- ence for the UE in order to perform synchronization and conduct downlink measurements, the UE follows the cell associated with the acquired frequency when in-coverage. The UE can indicate the current synchronization reference type to the eNB. One transmission pool for scheduled resource allocation is configured, considering the synchronization reference of the UE. For controlling channel utilization, the network can indicate how the UE adapts its transmis- sion parameters for each transmission pool depending on the channel busy ratio (CBR). The UE measures all configured transmission resource pools including the exceptional resource pool. If a resource pool is pre)configured such that a UE always transmits PSCCH and PSSCH in adjacent RBs, then the UE measures PSCCH and PSSCH resources together. If a resource pool is (pre)configured such that a UE may transmit PSCCH and the corresponding PSSCH in non-adjacent RBs in a subframe, then PSSCH resource pool and PSCCH resource pool are measured separately. A UE in RRC_CONNECTED state can be configured to report CBR measurement results. For CBR reporting, periodic reporting and event-triggered reporting are supported. Two reporting events are intr