coverage to ensure continuity of service delivery and the progressive rollout of 5G cells. It certainly seems the most plausible method of implementing 5G, while at the same time ensuring that the integrity of data connections is maintained in areas where the backhaul and network infra- structure have not yet upgraded to 5G. However, this requires UE by default to support simul- taneous dual uplink transmissions of LTE (1TX/1RX) and NR (2TX/2RX) carriers in all possible combinations of standardized bands and radio access technologies (FDD, TDD, SUL, SDL), which would increase the implementation complexity where multiple separate radios and bands functioning in a small device form factor. When combined with an LTE TDD anchor point, the network operation may be synchronous, in which case the operating modes will be constrained to 1TX/2TX and 1RX/2RX, or asynchronous which will require 1TX/ 2TX, 1TX/2RX, 1RX/2TX, 1RX/2RX. When the LTE anchor is an FDD carrier, the TDD/ FDD inter-band operation will require simultaneous 1TX/1RX, 1TX/2RX, and 2TX/1RX/ 2RX. In all cases, since control-plane information is transported over LTE radio bearers, it is critical to ensure that LTE anchor point uplink traffic is reliable [28]. The RF front-end developers try to mitigate the interference as much as possible to allow optimal signal transmission/reception in the UE. The complex nature of dual transmit LTE/ NR concurrency and 5G-capable UE constitutes an even greater challenge for the NR RF front-end. The second phase of NR Rel-15 deployments will include standalone operation, which uses a 5G core network that will not require backward compatibility to LTE. However, the assumption is that the initial implementation of 5G NR starts with non- standalone, which is the main deployment strategy for refarmed bands, since the standalone systems are anticipated to be deployed the spectrum above 3 GHz. 730 Chapter 5 The following is a list of key RF challenges that are foreseen as a result of the NR imple- mentations in sub-6 GHz: Wider ch