 OI ag WiFi BT 2/3/4G TRX IC MODEM Figure 12.22 High-level block diagram of the RF portion of a 5G UE supporting LTE and NR in FR1, NR in FR2, and all required wireless connectivity. 12.6 Examples of UE Implementation Challenges The block diagram here is not necessarily how a real implementation will work, and the interconnect is extremely simplified to show what is connected to what and, for example, does not show all the switches needed to support feature like SRS antenna switching and the different Tx/Rx paths modes. Also, it shows an implementation using only four antennas to support all the multiplexing and concurrent modes, but in most implementations, extra antennas will be added (especially for the higher FR1 bands as they are relatively small) to simplify the interconnect and multiplexing and provide fur- ther isolation between concurrent modes. In terms of concurrency, this block diagram illustrates one of the most complex sets from the new 5G NR features: In UL: Triple UL FR1 + FR2 EN-DC with concurrent operation of 2.4 GHz WiFi/ Bluetooth and 5 GHz WiFi (up to five simultaneous transmissions, including 2x2 UL MIMO in HB/UHB NR and 5 GHz WiFi) In DL: 4x4 DL MIMO in 2 FR1 bands + 3 Band 2x2 DL MIMO + FR2 polariza- tion diversity + 2.4 GHz WiFi/Bluetooth and 5 GHz WiFi + Global Navigation Satel- lite System (GNSS) (multiple band simultaneously) All these concurrent modes have to be supported with complex multimode cellular and connectivity RF transceivers with the addition of the IF transceiver needed for FR2 to provide the parallel BB signals to/from their respective modems, which further increases the number of RF connections. 12.6.2 FR2 Antenna Integration and Smartphone Design If the integration and performance of antennas have already been a challenge in smart- phones until now, the problem will be further exacerbated with the integration of the mmWave antenna array panels in 5G. Given that the phone aesthetics and design is a prime concern for a high-end smartphone, the material used (glass, metal 