Millimeter wave auctions push global TDD spectrum adoption to 53%

Recent auctions in high-frequency millimeter wave bands boosted the share of time division duplex spectrum to 53% of the 50 mobile markets that Kagan covered in 2020.

To view the complete list of spectrum allocation per market, download the attached spreadsheet (clients only).

Time division duplex, or TDD, and frequency division duplex, or FDD, are two alternative configurations for spectrum. While FDD uses separate frequencies for uplink and downlink communications, TDD separates uplink and downlink signals into alternating "chunks" delivered through the same frequency.

Currently, industry experts advocate for a hybrid FDD-TDD spectrum ecosystem. TDD's flexibility allows the allocation of more downlink capacity to meet asymmetric data usage, but FDD's coverage remains superior (holding all other factors constant). As the world moves toward higher-frequency bands and 5G, however, the need for higher capacity makes TDD more attractive.

China is one of the earliest and strongest advocates for TDD spectrum worldwide. It started its investment in TDD technology way back in the 3G era when it developed its own TDD standard, Time Division Synchronous Code Division Multiple Access or TD-SCDMA.

Legacy TDD infrastructure from the 3G era underpinned China's support for the Time Division Long Term Evolution or TD-LTE standard for 4G. China is now one of the largest backers of the Global TD-LTE Initiative or GTI, an international organization "dedicated to constructing a robust ecosystem of TD-LTE, speeding up the commercialization of TD-LTE and promoting the convergence of LTE TDD and FDD."

While China's TDD spectrum inventory is all on mid-band spectrum, the largest driver for TDD adoption worldwide is actually in mmWave spectrum. The U.S. is arguably the strongest supporter of mmWave spectrum for 5G, which exclusively runs on TDD. Among the 50 markets in our coverage, the U.S. had the largest TDD spectrum inventory as of the end of 2020, both in terms of bandwidth (6,550.6 MHz) and proportion (91% of total allocated spectrum).

The next four markets with the highest TDD spectrum bandwidth and proportion are all from the Asia-Pacific: Thailand, South Korea, Japan and Taiwan. It is no surprise then that Asia-Pacific is the leading region in terms of TDD spectrum bandwidth worldwide (13,953.3 MHz). In terms of TDD spectrum share, however, North America takes the top spot (83%) because of the U.S.

On the other end of our list, 10 markets still have not released TDD spectrum for mobile use as of the end of 2020: Bangladesh, Belgium, Brazil, Chile, Colombia, Jordan, Kenya, Mongolia, Pakistan, Peru and Vietnam.

High-band spectrum (millimeter-wave bands above 24 GHz)

The 26 GHz band was the most popular mmWave spectrum as of year-end 2020. While the 28 GHz enjoyed wider support in the early phase of 5G trials, the 26 GHz band gained the upper hand after the International Telecommunication Union or ITU officially sanctioned it for 5G in November 2019.

Canada, Finland, Germany, Hong Kong, Japan, Russia, South Korea, Taiwan, Thailand and the United Arab Emirates have some allocated mmWave spectrum in the 24 GHz, 26 GHz and 28 GHz bands.

The U.S. has the widest assortment of allocated mmWave bands, starting with the Local Multipoint Distribution Service or LMDS spectrum in the 28 GHz band and more recent allocations in the 24 GHz, 28 GHz and the Upper Microwave Flexible Use Service or UMFUS spectrum in the 37 GHz, 39 GHz and 47 GHz bands.

Mid-band spectrum (between 1 GHz and 6 GHz)

3.5 GHz is the most popular mid-band spectrum for 5G thanks to the lead of pioneer markets in Europe and the Asia-Pacific. The U.S. only joined the global mid-band 5G trend in 2020 with its release of the Citizens Broadband Radio Service or CBRS spectrum in the 3.5 GHz band and 3.7 GHz C-band for mobile services.

Most — but not all — markets use TDD configuration for the 3.5 GHz band. Popular adjacent bands 3.3 GHz and 3.7 GHz, on the other hand, run exclusively on TDD.

Legacy FDD bands 1.8 GHz, 2.1 GHz and 2.6 GHz still have the largest allocated bandwidth in most markets worldwide. Although some 3G-era licenses have expired in recent years, most markets chose to re-farm these bands for 4G. Some markets, such as Brazil even used mid-frequency FDD bands 1.8 GHz, 2.1 GHz and 2.6 GHz for 5G through Dynamic Spectrum Sharing or DSS due to the delayed release of 3.5 GHz spectrum last year.

Low-band spectrum (below 1 GHz)

Arguably, 700 MHz is currently the most prized low-band spectrum for mobile operators due to its good coverage and flexibility. The FDD version of the APT700 standard is the most popular configuration for the band worldwide. Only some markets such as Canada and the U.S. still use the US700 standard that allows for some TDD allocation.

Several 700 MHz auctions were originally slated for 2020 but were eventually postponed due to the COVID-19 pandemic. Some markets are still unable to use the band for mobile services because of incumbent analog television broadcast licenses. This explains why, as of the end of 2020, the 800 MHz and 900 MHz bands still have larger allocated bandwidths than the 700 MHz band.

Other less popular low-frequency bands are 450 MHz (active only in Indonesia, Mongolia and the Philippines) and 600 MHz (used for 5G in Canada and the U.S.).

Wireless Investor is a regular feature from Kagan, a media market research group within S&P Global Market Intelligence's TMT offering, providing exclusive research and commentary.

This article was published by S&P Global Market Intelligence and not by S&P Global Ratings, which is a separately managed division of S&P Global.