 Cases 8.1.1 Unlicensed and Shared Spectrum Unlicensed/license-exempt bands are a spectrum that has been defined for use collectively by an undetermined number of independent users without registration or individual permis- sion. For unlicensed bands, the regulatory bodies establish rules for how applications, tech- nologies, and industries must use the spectrum that allows applications and users to coexist with limited interference to each other. The rules are defined openly with no limitation on technologies and applications other than requirements to avoid/reduce destructive interfer- ence. With unlicensed spectrum, there is no process for establishing the right of use, and therefore the band may be utilized by any device that is compliant with usage rules such as 848 Chapter 8 maximum power levels, bandwidth limitations, and duty cycles. The use of unlicensed spec- trum is an important complement for all 5G systems and deployments, particularly in small cell deployments. Table 8.1 provides a summary of such rules for 5 GHz band utilization across the world [9,13,15,21]. In recent years, short-range communication technologies such as Bluetooth, 3 ZigBee, 4 Wi-Fi have utilized unlicensed bands for short-range communication services. The fre- quency mapping of unlicensed bands is country dependent, which determines the type of technology used within designated parts of the spectrum. Despite the original intent, radio communications in the ISM bands are possible as long as the communication systems are designed to tolerate the inter-user interference as well as the cochannel interference poten- tially from other communication systems operating in the same band. Since the advent of mobile devices, more and more short-range, low-power, low-cost wireless communication systems, such as cordless phones, Wi-Fi, Bluetooth, and ZigBee, have utilized some of the unlicensed bands in 902-928 MHz, 2.40-2.4835 GHz, and 5.725-5.875 GHz. The grow- ing number of wireless applications in the ISM bands has motivated the wireless i