19 LTE transmission procedures The LTE uplink and downlink transmission schemes have been described from a physical layer perspective in Chapters 16 and 17. In this chapter, some proce- dures and protocols required for data transmission, for example, retransmission protocols, scheduling, and uplink power control, will be described. 19.1 RLC and hybrid-ARQ protocol operation In LTE, retransmissions of missing or erroneous data units are handled primarily