he two transmitters. In Release 16, this limitation is removed, and the Release 16 UE does not require time synchronization between different 5G gNBs in case of dual connectivity, as covered in Chapter 15. The example use case for 5G-5G dual connectivity, which has been discussed in 3GPP as well, has been the dual connectivity operation with the 3.5 GHz and 28 GHz bands, as shown in Figure 6.52. This would allow the full benefit of the 5G core features to be obtained as well as low latency and high reliability with 5G while at the same time benefiting from the very high data rates with mmW spectrum. With this example, one could get on the order of 2 Gbps from the 3.5 GHz band (with 100 MHz carrier available), and a single 400 MHz channel available in the 28 GHz band could provide a user data rate on the order of 3 Gbps. Thus, combined, this would enable a downlink peak data rate of 5 Gbps. The detailed peak rate depends further, for example, on the uplink/downlink allocation ratio, as addressed further in Section 6.15. With standalone 5G operation, naturally all the uplink transmission power can be dedicated for 5G operation without the need to coordinate between the LTE and 5G transmitters. A special case can arise for difficult band combinations, when the UE would be operating in the time division multiplexing (TDM) mode between LTE and 5G to avoid interference. This could be needed, for example, if the actual carriers chosen on the LTE side would cause interference with the actual carriers used on the 5G band. In Europe, the problem could arise with some of the allocations on the 1800 MHz band if the allocation on the 3.5 GHz spectrum coincides exactly with the second-order harmonics. The TDM operation would also impact the network side and reduce LTE and 5G performance due to the longer delay, as the uplink is not always available due to the TDM operation. Also, the performance on the LTE side is reduced, and one needs to delay uplink HARQ feedback compared to the normal operation. An example of 5G core 5G se