sed band provides a lot more downlink capacity and higher data rates. This solution fits very well with the typical traffic patterns where the downlink traffic is 10 times more than the uplink traffic. Therefore, it is beneficial to use the new spectrum blocks mainly for the downlink direction. The second phase of LAA, Enhanced LAA (eLAA) standardized in Release 14, also includes uplink transmission on the unlicensed Licensed spectrum Unlicensed spectrum 700-3800 MHz 5 GHz Uplink Downlink Downlink Figure 16.11 Supplemental downlink at unlicensed bands. 16.3 LTE-Advanced Pro Technologies Figure 16.12 LTE-Wi-Fi aggregation (LWA). Wi-Fi access eNodeB point band. LAA was commercially deployed in networks and devices starting 2017 including iPhones starting in 2018. LTE-Advanced Pro also allows the aggregation of LTE and Wi-Fi transmissions, offer- ing another solution for utilizing unlicensed bands. So far, LTE and Wi-Fi interworking has been implemented on the application layer. 3GPP Release 13 allows dual connec- tivity of LTE and Wi-Fi on the radio layer, which makes the offloading of data traffic to Wi-Fi more efficient. The LTE eNodeB splits data traffic between LTE and Wi-Fi trans- missions. The user device can then receive data simultaneously via both LTE and Wi-Fi, thereby aggregating the spectrum of the LTE eNodeB, and of the Wi-Fi access point. The data transmission can be dynamically split between LTE and Wi-Fi instead of using slow switching between the technologies. Wi-Fi radio can be utilized to the maximum while still maintaining the connection to LTE for reliable mobility and connectivity. The LWA solution is illustrated in Figure 16.12. The commercial interest in LWA has remained low. 16.3.3 Enhanced Spectral Efficiency with 3D Beamforming and Interference Cancelation LTE has provided high spectral efficiency since its introduction. The downlink efficiency of LTE has been boosted further via MIMO technology, including 4x2 MIMO, 8x2 MIMO, and 4x4 MIMO, and with interference cancelation. LTE-Advanced P