.9 GHz. These bands, which are all based on TDD or unpaired spectrum, generally have wider bandwidth than their 4G predecessors. They will be particularly important in user equipment implementations that will use LTE as the anchor (or primary) and the NR as a secondary access scheme (i.e., NSA deployments). 5G systems can also use sub-1 GHz FDD bands to provide wide-area coverage, including deep indoor penetration. The low-band spectrum can take advantage of the new 700 MHz allocation in Europe or 600 MHz allocation in the United States, as well as the refarming of 850/900 MHz released by minimizing the use of legacy 2G/3G spectrum. The aggregation of the different spectrum bands from sub-1 GHz to millimeter waves provides the best com- bination of coverage, capacity, and user data rates. In addition to the licensed bands in the 3-6 GHz range, there is the possibility of using supplemental unlicensed bands to create even wider operating bandwidth. The 3GPP NR will utilize mmWave spectrum to achieve wider bandwidths and higher data rates. Industry consensus is building around the use of mmWave spectrum for fixed wireless applications due to challenges of mobility manage- ment in very high frequencies. Applying mmWave technology to mobile devices represents a significant technological challenge for the near future. Small cells are going to be a criti- cal part of the 5G network deployments. We referred to this trend earlier as network densifi- cation. The use of mmWave does leverage large antenna arrays and directional beams in the downlink over a short range, enabling design of high-capacity small cells. Spectrum harmonization remains an important issue for the development of 5G and even more important for higher frequencies in order to support the development of a new ecosys- tem as well as the deployment of massive MIMO systems. The United States has adopted new rules to enable rapid development and deployment of 5G technologies and services in licensed spectrum in 28 and 39 GHz. China is also planning to deploy