 shows that up to 15% PA power consumption savings may be achieved by using QPSK CP-OFDM VS. QPSK DFT-S-OFDM. UL MIMO is therefore bound to play an important role to meet the high cell-edge spectral-efficient targets of 5G. From a UE RF front-end perspective, the price to pay for this feature is to double the number of transmitter paths, that is, two power amplifiers and two separate antennas (the Rx diversity antenna can be reused for UL diversity). Due to the limited space for additional antennas (Figure 12.7), and Right Main 1 (M1): [Tx/Rx] LB (663-960 MHz) MB (1710-2200 MHz) HB (2305-2690 MHz) Main 2 (M2): [Tx/Rx] HB (2305-2690 MHz) Div. 1 (D1): [Rx Div] [4x4 MIMO 1] MB/HB Div. 2 (D2): [Rx Div] MB + GPS extractor [4x4 MIMO 2] MB/HB o max Bottom Div. 3 (D3): [4x4 MIMO 3] MB/HB Div. 4 (D4): [4x4 MIMO 4] HB W1 W2: WiFi dual-band + 3GPP LAA (B46) D> avg. Figure 12.7 Number of antennas in FR1 (left, div: receiver diversity, LB: low-band, MB: mid-band, HB: high-band), survey of smartphone height. Back mmw Edge mmW Module 1 Module 2 39 GHz FR1 RF Front-end vertical 28 GHz IF lines lines modules FR1 1 & IF FR1 & IF transceiver transceiver RF... Multiple RF modem lines modem lines interconnections Edge mm Edge mmW Module 1 Module 3 x8 horizontal 4G/5G Sub-6GHz Modem Transceiver IF lines Front mmW () () Module 2 Multiple IQ links Example of dual-polarization, dual-band mmw transceiver Digital serial Multiple IF links or analog IQ [6-10GHz] x2 Example of mmw antenna module eg. panel #1 Figure 12.8 (Left) Impact of mmWave support on a 5G smartphone high-level architecture, (right) example of mmWave antenna module using eight antenna elements per band of operation and RF phase shifting. 12.2 Impact of New Physical Layer on RF Performance since good MIMO performance requires low antenna correlation [8], this feature can only be practically supported in mid- and high-frequency bands (MB/HB). Dual-PA architectures (Figure 12.4) may also help deliver better uplink coverage due to (1) reduced IMD levels thanks to antenna-to-an