mount of available spectrum is typically in Europe, in advanced Asian markets like Japan, Korea, and Australia, and in China. The lowest amount of available spectrum is typically in India, in developing Asian markets, like Indonesia, and in Africa and Latin America. The reason is that part of the spectrum is not available for mobile operators. Another reason is that the number of operators may be more than three. This entire spectrum is not available for Long-Term Evolution (LTE) yet because legacy 2G and 3G networks need to be maintained in most markets, and they eat part of the spectrum. This is especially true in developing markets, where the share of legacy devices is still substantial. The available spectrum will increase considerably with the allocations of 3.3-5.0 GHz bands. More spectrum at 700-2600 MHz will also be made available gradually in those markets where part of the spectrum is unallocated. Operator consolidation will also increase the amount of spectrum per operator. When all these factors are considered, the typical available spectrum will increase to 300 MHz per operator in the near future. 8.2.1 Spectrum Refarming and Dynamic Spectrum Sharing Spectrum refarming refers to the process of migrating blocks of spectrum from one technology to another. Spectrum refarming has been done from 2G to 3G and to LTE, and refarming will continue to 5G. Typical spectrum strategy evolution is illustrated in Figure 8.2. The target has been to minimize the spectrum allocation for legacy 2G and 3G technologies. Some operators have been able to close down legacy networks, while many operators still keep 2G and 3G running to maintain legacy devices, old Internet of Things (IoT) devices, and to provide circuit-switched (CS) voice support. 2G and 3G systems are mostly maintained at the 900 MHz band. The other bands between 700 and 2600 MHz have been refarmed to LTE to provide more capacity and higher data rates. 5G introduction in many markets happens with the 3.5 GHz band and with some low bands like 700 MHz. The n