.6. In total more Terrestrial Broadband Wireless Telecommunications Downlink frequency frequency Base station Mobile (FDD) Common uplink frequency Base station Mobile (TDD) Figure 10.5 FDD and TDD modes Sub 1 GHz 1.7 GHz 1.9 1.92 GHz 1.92 ~ 1.98 GHzt 2G/3G/4G 3G/4G: FDD 3G: TDD 3G: FDD 450 MHz 1.72 1.78 Europe, China Europe, Japan, 700 MHz Worldwide Korea Korea, China 800 MHz bands TDD or FDD Various worldwide 2.01 ~ 2.025 GHz 2.11 ~ 2.17 GHz 2.3 2.4 GHz 2.4 2.48 GHz 2.5 ~ 2.69 GHz 3G: TDD 3G: FDD 3G/4G: TDD 3G/4G: Europe, Japan, Europe, Japan, China Worldwide Europe, Japan, Korea Korea, China Korea, China Mobile Internet TDD or FDD Korea 3G/4G: USA, Canada TDD or FDD 3.3 3.8 GHz 3.65 ~ 3.69 GHz 5.2 ~ 5.8 GHz 3G/4G Unlicensed band: 3.3 3.4 GHz: China, India nomadic services (WLAN) 3.4-3.6 - GHz: Worldwide Various part of the band is 3.6-3.8 - GHz: USA, Canada used in a different regions of TDD or FDD the world Figure 10.6 Several mobile communications system frequency bands than 1 GHz of frequency bandwidth has now been allocated to mobile (broadband) communications to satisfy the demand for broadband wireless services at the time of writing (2015). The frequency bands allocated to mobile and broadband services are suitable as they allow for large possible bandwidths, small size antennas as well as low path loss. In general very little capacity is free in frequency bands below 450 MHz, and frequencies above 3-5 GHz experience very large path loss, making them unsuitable for long-distance terrestrial commu- nications as will be explained below. Frequency allocation to different mobile operators therefore follows strict business and policy guidelines to ensure this scarce resource is efficiently utilised. Broadband Telecommunications Technologies and Management Terrestrial Channel Characteristics Some radio channels are characterised by line-of-sight signal propagation, that is, nothing blocks the path between a transmitter and a receiver. An example of such a channel is satellite communications links where nothing