0, 40, 50, 60, 70, 80, 90) as shown in Fig. 8.36. If the UE transmits on 4 out of the 10 available RBs per interlace L = 4, then the RIV is calculated as RIV = N(L - 1) + RB start. With N = 10, RB start can have a value between 0 and 6 and RIV can be between 30 and 36. The RIV is signaled via DCI to the UE. In addition to this and other information, the DCI format also includes the method on how to access the channel, that is, how to perform LBT in the uplink. As shown in Table 8.3, there are two channel access types defined for eLAA, whose usage is signaled with the uplink scheduling grant (DCI formats 0A, OB, 4A, 4B). The type 1 channel access procedure is identical to the procedure for LAA. The difference is that there are separate Chapter 8 Interlace 0 Interlace 9 Interlace 0: (0,10,20,...,90) Interlace 1: (1,11,21,...,91) Interlace 9: (9,19,29,...,99) Figure 8.36 eLAA interlaces for 20 MHz LTE channel 22]. channel access priority classes defined for the uplink. Type 2 is a procedure similar to trans- mitting DRS in the downlink. After sensing that the channel is idle for 25 us, the device can start its PUSCH transmission [22]. It must be noted that DCI format 0A is used for the scheduling of PUSCH in an LAA SCell and DCI format 0B is used for the scheduling of PUSCH in each of the multiple subframes in an LAA SCell. Furthermore, DCI format 1C is used for very compact scheduling of one PDSCH codeword, notifying multicast control channel change, notifying single-cell multicast control channel change and direct indication, reconfiguring TDD, and LAA common information, whereas DCI format 4 is used for the scheduling of PUSCH in an LAA SCell with multi- antenna port transmission mode. DCI format 4B is used for the scheduling of PUSCH with multi-antenna port transmission mode in each of the multiple subframes in an LAA SCell. The LTE-based LAA supports two alternative approaches to multi-carrier LBT. In the first approach, the eNB is required to designate a carrier requiring LBT with random backoff and the eNB ca