) protocol of the AMF in 5GC (see Chapter 5). In addition to the mechanisms required to handle the new aspects of the 5G physical layer, the key drivers for making changes over the LTE baseline for the radio protocols 7.3 SDAP were (1) the need to deal with a combination of even larger data rates and lower latency than in earlier generations; (2) the provision of dynamic spectrum usage; and (3) the sup- port for a new QoS framework from 5GC. In the following, the main changes introduced for those key drivers are summarized. First, in order to support a combination of large data rate and low latency, the 5G radio protocols were optimized for UE processing. The processing requirements are constrained by real-time operations. In the uplink, this means the operations that need to be performed by the UE to build an uplink transport block once it receives a grant from the network. In order to relax the processing requirements, real-time operations were pushed down the radio protocols and located as closely as possible to the physical layer to allow as much processing as possible without knowing the grant size, that is, to allow as many non-real-time operations and as much pre-processing as possible. Max- imizing the number of non-real-time operations also makes parallel processing easier, which is essential to reduce battery consumption. The main changes introduced in 5G radio protocols compared to LTE to ease UE processing are as follows: RLC concatenation moved to MAC (the building of RLC PDUs becomes a non-real-time operation - see Section 7.5). Asymmetric placement of MAC CEs in Uplink and Downlink (the processing of MAC CEs becomes easier for the UE - see Section 7.6.13). Interlacing of subheaders in MAC (pipeline processing of MAC PDUs is made possi- ble - see Section 7.6.13). Furthermore, reordering operations in the radio protocols were streamlined with only PDCP reordering packets (reordering windows were previously located in both RLC and PDCP in LTE). Without having to reorder packets in RLC, PDCP can now de