When deployed, 5G networks should deliver more speed and capacity to support massive machine-to-machine communications and to provide low-latency (delay), high-reliability service for time-critical applications. Based on trials to date, 5G networks are starting to demonstrate high performance in different scenarios such as dense urban areas and indoor hotspots.
With these ambitious goals, 5G networks face considerable challenges. The increased capacity and data rates promised by 5G require more spectrum and vastly more spectrally efficient technologies, beyond what is currently used in 3G and 4G systems.
Some of this additional spectrum will likely come from frequency bands above 24 GHz, which pose considerable challenges. The first challenge refers to the intrinsic propagation characteristics of millimeter waves. These radio waves propagate over much shorter distances than those of medium- (between 1-6 GHz) and low- (below 1 GHz) frequency bands.
Hence, coverage of a given area will require a significantly increased number of base stations that will increase the complexity of the infrastructure, including the need to deploy radio equipment on street facilities, such as traffic lights, lampposts, utility poles and power supplies.
Another challenge relates to 5G connection links between base stations and the core network (backhaul), which rely both on fiber and wireless technologies. Considerable work is required for implementing fiber services and ensuring availability of wireless backhaul solutions with sufficient capacity, such as microwave and satellite links, and potentially with high-altitude platform stations (HAPS) systems where they are deployed.
Furthermore, spectrum is a scarce and very valuable resource, and there is intense – and intensifying – competition for spectrum at the national, regional and international levels. As the radio spectrum is divided into frequency bands allocated to different radiocommunication services, each band may be used only by services that can coexist with each other without creating harmful interference to adjacent services.
ITU-R studies examine the sharing and compatibility of mobile services with a number of other existing radiocommunication services, notably for satellite communications, weather forecasting, monitoring of Earth resources and climate change and radio astronomy.
National and international regulations need to be adopted and applied globally to avoid interference between 5G and these services and to create a viable mobile ecosystem for the future — while reducing prices through the global market's economies of scale and enabling interoperability and roaming. The additional spectrum to be used by 5G therefore needs to be identified and, possibly, harmonized at global or regional levels. For similar reasons, the radio technologies used in 5G devices need to be supported by globally harmonized standards.