nsmission and retransmission; and 2-bit sidelink index [this field is present only for TDD uplink/downlink configuration 0-6]. When DCI format 5A CRC is scrambled with sidelink semi-persistent scheduling V-RNTI (SL-SPS-V-RNTI ), it would further include 3-bit sidelink SPS configuration index and 1-bit activation/release indication [4]. For sidelink transmission mode 1, if a UE is configured via RRC signaling to receive DCI format 5 with the CRC scrambled by the SL-RNTI, the UE is required to decode PDCCH/ ePDCCH according to the combination defined in Table 7.4. For sidelink transmission mode 3, if a UE is configured by higher layers to receive DCI format 5A with the CRC scrambled by the SL-V-RNTI or SL-SPS-V-RNTI, the UE must decode the PDCCH/ePDCCH according to the combination defined in Table 7.4, and it is not expected to receive DCI format 5A with size larger than DCI format 0 in the same search space that DCI format 0 is defined. The PSCCH carrying SCI format 0 is transmitted in two subframes within the configured resource pool occupying only one RB pair. The 7-bit time resource pattern determines Semi-persistently scheduled sidelink transmission for V2X sidelink communication, which is used for activa- tion, reactivation, deactivation, and retransmission. Vehicle-to-Everything (V2X) Communications 827 Table 7.4: PDCCH/ePDCCH configured by various RNTIs [5]. DCI Format Search Space DCI format 5 For PDCCH: Common and UE-specific by C-RNTI For ePDCCH: UE-specific by C-RNTI DCI format 5A For PDCCH: Common and UE-specific by C-RNTI For ePDCCH: UE-specific by C-RNTI which subframes are used for transmission of PSSCH. A subframe indicator bitmap of vari- able length is defined, where the length of this bitmap depends on the duplex mode; i.e., FDD or TDD, and in case of TDD which UL/DL configuration is used. In case of FDD, the bitmap is 8 bits long. Up to 128 different time resource patterns define how these 8 bits are used. The RB allocation for PSSCH follows the same principles defined for LTE Rel-8 while inter