istance/duplex gap such as bands 5, 8, and 12, this leads to additional maximum sensitivity degradation (MSD) issues as discussed in Section 12.3.3.1. Further band extensions are requested for Release 16, with, for example, the request to support 50 MHz CBW in n7, thereby creating additional MSD challenges for the RF front-end. In bands n3, n7, n38, n41, n77, n78, and n79, it is mandatory for the UE to support four receive antennas (cf. note 1 in Figure 12.10). The only allowed exception to this rule has been granted to vehicular UEs in order to account for cost/implementation trade-offs. 3GPP analyses have shown that thanks to the higher performance of rooftop mounted antennas, the link budget for 2RX vehicular UEs is similar to that of smartphones with for four low profile, built-in antennas [8]. n40, n41, n77, n78, and n79 are the most attractive bands since 100 MHz CBW is supported at SCS 30 and 60 kHz, thereby paving the way to exploit fully the promises of the 5G physical layer. 12.3.3.1 Impact of Extended Channel Bandwidth on MSD in Refarmed Bands Similar to previous studies done, for example, in the LTE band 12/17, in bands with a short duplex distance and short gaps, increasing the transmitter CBW places the PA Tx noise leakage in too close proximity to the UE's own downlink carrier to prevent receiver self-desensitization. The measurements in Figure 12.11 have been performed taking into account only the counter-intermodulation order 3 (counter-IM3) products at the PA input (Figure 12.11 left). The resulting MSD is 0.8 and 1 dB for 20 MHz cell bandwidth operation in bands 8 and 5, respectively [9]. Recent 3GPP contributions have requested to increase these MSD levels to account for the presence of additional counter-IM5 products that may be present at the PA input port. Depending on the counter-IM5 rejec- tion ratio, an increase in the transmitter excess noise level can be expected due to (1) the short Tx-Rx frequency separation inherent to bands n8 and n5 and (2) the fact that the counter-IM5 PSD extend