Standards and spectrum for international mobile telecommunications

ITU standards development for IMT-2020 is well underway, along with the associated spectrum management aspects.

The dramatic increase in availability and accessibility of mobile communications in recent years is due, to a large extent, to the development of international standards and the identification and global harmonisation of frequency bands for the operation of international mobile telecommunications (IMT), thereby enabling interoperability, roaming and global economies of scale.

Standards

Second-generation mobile telephone systems were developed in the late 1980s and initially deployed in the early 1990s. The transition from the first to the second generation of mobile phones was certainly characterised by the change from analog to digital communications, but it was also characterised by the growing requirement for these systems to operate seamlessly on a regional, if not global, basis.

Regional/global operation of these systems was hampered by having multiple incompatible standards, as well as different frequency bands and channel arrangements, being used in different parts of the world. This in turn had a significant impact on the cost, and thus affordability, of these systems. Recognising this, the ITU membership established a group of experts to study the requirements of future public land mobile telecommunications systems (FPLMTS).

Studies on FPLMTS were conducted in the CCIR (the former ITU Radiocommunication Sector (ITU–R)) Interim Working Party 8/13, with the first substantive outcome being a decision by the 1992 World Administrative Radio Conference to identify specific frequency bands for the operation of FPLMTS. The studies then focused on developing the set of detailed radio interface specifications for FPLMTS.

ITU–R Task Group 8/1 was established to develop these 3G radio standards, which were finally approved in May 2000 in Recommendation ITU–R M.1457 — ‘Detailed specifications of the terrestrial radio interfaces of International Mobile Telecommunications-2000 (IMT-2000)’. The name change from FPLMTS to IMT and the principles and process for the further development of IMT were established by the ITU Radiocommunication Assembly 2000 in ITU–R Resolutions 56 and 57.

ITU–R Working Party 5D was subsequently established to continue the work on IMT. In close collaboration with the relevant national and regional standards development organisations, a yearly update process for IMT-2000 was applied to cater for the evolution and enhancement of the standard.

ITU–R Recommendations were also developed to address the implementation aspects of IMT-2000, such as global circulation of terminal equipment, radiofrequency channel arrangements and sharing studies between IMT and other radio services.

At the same time, ITU–R Working Party 5D initiated work to address the need for a global platform on which to build the next generation of mobile services — fast data access, unified messaging and broadband multimedia: IMTAdvanced. The IMT-Advanced radio interface specifications were finalised in 2012 and are specified in Recommendation ITU–R M.2012. These 4G systems are currently being deployed throughout the world, and it is expected that these systems will continue to evolve and be enhanced in the coming years.

With an eye to the longer-term requirements, in 2012 Working Party 5D commenced studies on the next phase of development: IMT-2020. It is planned to finalise the IMT-2020 specifications (5G) in the year 2020.

Spectrum

Where radio systems are to be used globally, it is highly desirable for existing and newly allocated spectrum to be harmonised. The benefits of spectrum harmonisation include: facilitating economies of scale, enabling global roaming, reducing equipment design complexity, preserving battery life, improving spectrum efficiency and potentially reducing cross-border interference.

Mobile devices typically contain multiple antennas and associated radiofrequency front ends to enable operation in multiple bands to facilitate roaming. While mobile devices can benefit from common chipsets, variances in frequency arrangements necessitate different components to accommodate these differences, which leads to higher equipment design complexity and cost.

Consequently, harmonisation of spectrum for IMT leads to simplification and commonality of equipment, which is desirable for achieving economies of scale and affordability of equipment.

As mentioned previously, it was by a decision at the 1992 World Administrative Radiocommunication Conference (WARC‑92) that the first specific frequency bands for the operation of FPLMTS (now IMT) were identified in the ITU Radio Regulations, the international treaty governing the use of the radiofrequency spectrum and satellite orbits.

Identification of a frequency band in the Radio Regulations does not afford any priority for such use with respect to other radio services allocated to that spectrum, but it does provide a clear signal to the national regulators for their spectrum planning. It also provides a degree of confidence for equipment manufacturers and network operators to make the long-term investments necessary to develop IMT in these bands.

No single frequency range satisfies all the criteria required to deploy IMT systems, particularly in countries with diverse geographic and population density; therefore, to meet the capacity and coverage requirements of IMT systems, multiple frequency ranges are needed.

Since WARC‑92, successive World Radiocommunication Conferences, in 1997, 2000, 2007 and 2015, have periodically identified additional frequency bands for IMT within the range of 450 MHz to 6 GHz to cater for the rapidly growing demand for mobile communications, particularly mobile broadband data.

While the 2015 World Radiocommunication Conference made good progress in identifying additional frequency bands and globally harmonised arrangements below 6 GHz for the operation of IMT, it also recognised a potential future requirement for large contiguous blocks of spectrum at higher frequencies for these systems. Consequently, it called for 11 frequency bands within the range 24–86 GHz to be studied by ITU–R as bands that may be identified for use by IMT at the World Radiocommunication Conference in 2019 (WRC‑19). The focus of these studies is to identify a limited subset of these bands that are recommended to be identified globally for use by IMT.

Conclusion

The scope of 5G is much broader than the previous generations of mobile broadband communication systems. We are talking here about not just an enhancement to the traditional mobile broadband scenarios, but extending them to use cases involving ultra-reliable and low-latency communications, and massive machine-type communications.

ITU’s work in developing the standards for IMT-2020, in close collaboration with the whole range of 5G stakeholders, is now well underway, along with the associated spectrum management and spectrum identification aspects.

Republished with permission from ITU News magazine.

Image credit: ©stock.adobe.com/au/jeffreyjcoleman

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