5 GHz), and discovery reference signals (DRS) to enable radio resource manage- ment. In discontinuous transmission, the first subframe in a burst can last 1 ms (starts at symbol 0) or 0.5 ms (starts at symbol 7), which is signaled to the UE via RRC message subframeStartPosition in the dedicated physical configuration. The last subframe in a burst can last 1 ms or the duration of a special subframe with normal cyclic prefix (3, 6, 9, 10, 11, 12) OFDM symbols, which is signaled to the UE via DCI format 1C scrambled with CC-RNTI [8]. In LAA, the configured set of serving cells for a UE always include at least one SCell oper- ating in the unlicensed spectrum. The LAA SCells act as regular SCells where the eNB and the UE use LBT before performing transmission in the SCell. The combined time of trans- missions by an eNB may not exceed 50 ms in any contiguous 1 second period on an LAA SCell. The LBT type (i.e., type 1 or type 2 uplink channel access) which the UE applies is signaled via uplink grant for physical uplink shared channel (PUSCH) transmission on LAA SCells. For type 1 uplink channel access on autonomous uplink (AUL)7, the eNB signals the channel access priority class for each logical channel and the UE must select the lowest channel access priority class of the logical channel(s) with MAC SDU multiplexed into the MAC PDU. The MAC control elements, except padding buffer status report (BSR), use the highest channel access priority class. For type 2 uplink channel access on AUL, the UE In autonomous uplink, uplink transmissions are allowed without requiring a prior scheduling request or an explicit scheduling grant from the eNB. Operation in Unlicensed and Shared Spectrum ((Q)) Unlicensed SCells User IP packets 12345 Unlicensed band 54321 Licensed PCell licensed Figure 8.12 Illustration of LAA operation concept [18]. may select logical channels corresponding to any channel access priority class for uplink transmission in the subframes signaled by eNB in common downlink control signaling. For uplink LAA operatio