Operation and maintenance Best effort (BE) High-throughput data Best effort (BE) Standard Best effort (BE) Low-priority data Background (BK) 5 QoS for Mobile Ultra-Broadband 5.5 WiFi vs. LTE/LTE-Advanced in Unlicensed Bands: The QoS Viewpoint The LTE mobile networks in the 4G era have also entered the unlicensed frequency bands where WiFi has been the dominant technology since the end of the 1990s. From 3GPP Release 12, each next release further specifies the use of LTE in unlicensed bands with different purposes, SO we have the following technologies (Figure 5.10): LTE in unlicensed spectrum (LTE-U). This is first version of LTE in unlicensed bands which has been standardized in 3GPP Release 12, and it is backward compatible with all 4G releases from 3GPP (i.e. Release 10 and beyond). It uses 5 GHz unlicensed band, and it is targeted to add capacity to the LTE network by using it on a 5 GHz unlicensed spectrum besides the licensed one. Of course, it coexists in this spectrum with WiFi, which operates on 5 GHz. Licensed assisted access (LAA). This was introduced with 3GPP Release 13 in 2015, as part of LTE-Advanced-Pro. It provides aggregate simultaneous use of LTE in licensed and unlicensed spectrum bands in the downlink direction to provide the most effi- cient use of both available bands. This is targeted to give higher bitrate in the range of Gbit/s with a single LTE carrier of 20 MHz and unlicensed 5 GHz band, provid- ing a better user experience. Enhanced LAA (eLAA) from 3GPP Release 14 allows licensed and unlicensed spectrum aggregation in the uplink, in addition to the down- link aggregation by the LAA. Long term evolution WiFi link aggregation (LWA). This enables aggregation of LTE in a licensed band and WiFi carrier, which is easy for implementation with legacy LTE and WiFi equipment. However, LWA lacks use of LTE in unlicensed bands [10]. MulteFire. This is fully operational use of LTE in an unlicensed spectrum on 5 GHz, specified by the MulteFire Alliance [11], which is different than LAA and LWA, whi