tilized for flexible refarm- ing. The main LTE bands in the current networks are illustrated in Figure 4.15: the left side shows typical bands in Europe, and the right side shows typical bands in Americas. The frequencies used in the Asia Pacific region are a mix of these two cases. 703 MHz 748 MHz 758 MHz 803 MHz 700 MHz Asia Pacific Uplink Downlink 703 MHz 788 MHz 700 MHz Europe Uplink Downlink 617 MHz 698 MHz 600 MHz Uplink Uplink Figure 4.14 Mainstream 5G low bands at 700 MHz (band n28) and 600 MHz (band n71). SDL = Supplemental Downlink. 4.5 Unlicensed Band Europe Americas 2600 MHz Band 7+38 / 41 2600 MHz Band 41 2300 MHz Band 40 2300 MHz Band 30 2100 MHz Band 1 2100 MHz Band 4 / 66 1800 MHz Band 3 1900 MHz Band 2 1500 MHz Band 32/50/51 900 MHz Band 8 800 MHz Band 20 850 MHz Band 5 / 26 700 MHz Band 28 700 MHz Band 12-14,17 600 MHz Band 71 Figure 4.15 Main LTE frequency bands. Relative coverage VS. 800 MHz 2100 MHz uplink 1800 MHz uplink 1500 MHz downlink 800 MHz uplink 700 MHz uplink -15.0 -10.0 Figure 4.16 Coverage of 1500 MHz supplemental downlink. One potential new frequency for 5G could be the 1500 MHz supplemental downlink band, which has a total bandwidth of 90 MHz. This band is an attractive solution for providing more downlink capacity with wide area coverage. Figure 4.16 illustrates the relative coverage. The 1500 MHz downlink has similar or better coverage as the 700 and 800 MHz uplinks. Therefore, 1500 MHz can be efficiently used for capacity boosting in those cells where large coverage and deep indoor penetration are required. Unlicensed Band The unlicensed 5 GHz band offers a lot of spectrum, as shown in Figure 4.17, even over 500 MHz, which is substantially more than any operator has in terms of licensed spectrum. 3GPP has specified band 46 covering 775 MHz at 5150-5925 MHz. The use of unlicensed spectrum is governed by some regulatory requirements, such as being able 4 Spectrum United = 580 MHz States Europe Japan = 455 MHz India China = 325 MHz Figure 4.17 5 GHz unlicensed band. to detect if