 and also on the baseband capability in terms of the max- imum number of parallel MIMO streams. The 5G downlink spectral efficiencies for dif- ferent configurations are summarized in Figure 10.58. The efficiencies naturally depend also on the propagation environment, cell size, network optimization, and algorithms. We want to illustrate the expected efficiencies and the impact of the main design param- eters. The target is to show the technology capability in optimized cases. The results are based on the number of simulations and field measurements. The following assumptions are used for obtaining the numbers: LTE 2 X 2MIMO efficiency is 1.7 bps/Hz/cell. 5G gain over LTE is 30% at low bands. 4RX UE gives 30% gain over 2RX UE. 4TX and 8TX gains over 2TX in downlink are 40% and 80%. Massive MIMO with 64TX gives 250% gain over 2TX. 64TRX efficiency is 30% more than 16TRX efficiency. 64TRX efficiency is 10% more than 32TRX efficiency. Doubling the number of MIMO layers gives 5% more capacity. 10.9.3 Uplink Spectral Efficiency The typical traffic asymmetry in LTE networks today is 10:1, which means that the down- link data volume is 10 times more than the uplink data volume. The downlink direction is the bottleneck in FDD deployments, but the importance of uplink efficiency grows in TDD, where a larger part of the frame is allocated for the downlink direction. The uplink efficiency in 5G is improved by using Orthogonal Frequency Division Multiple Access 5G spectral efficiency Massive MIMO 2 layers 4 layers 8 layers 16 layers Figure 10.58 Summary of 5G downlink spectral efficiency. 10.9 Spectral Efficiency and Capacity 5G uplink spectral efficiency 16TRX 32TRX 64TRX Non-massive MIMO Massive MIMO Figure 10.59 Uplink spectral efficiency with different antenna configurations. (OFDMA) compared to a single carrier in LTE. The single carrier solution is fine for the coverage-optimized cases and for low spectral efficiency. OFDMA gives a clearly higher efficiency than the single carrier. A generic uplink spectral efficiency t