With the development of TD-LTE, the shortage of TD-LTE spectrum resources has gradually surfaced. There are many domestic spectrum resources and the international share is small. There is a "digital dividend" 700MHz frequency band is called home in the remote, "nail households." "PHS's withdrawal from the grid is intermittent. In response, He Ting-run of the National Institute of Radio Frequency Spectrum Management stated that spectrum sharing, especially dynamic sharing, would be the best choice for resolving contradictions.

TD-LTE spectrum resources more or less

At present, China plans a total of 795 MHz for IMT systems, including a total of 170 MHz in the 2G era and 625 MHz in the 3G/4G era. The TDD band is concentrated in the 3G/4G era, with a total of 445 MHz, accounting for 71% of the total. Therefore, the TDD spectrum is viewed from the domestic perspective. The proportion is still relatively high.

On the contrary, in the international community, the spectrum planned for TDD is very small. For example, IMT bands have been planned in Europe. Although the proportion of TDD bands in high-frequency plans is increasing year by year, the overall trend is still FDD, and TDD is expected to be a supplement. In addition, there is no TDD plan at the low frequency of <1GHz. Canada and the United States plan to use the 2.5GHz band for the development of TD-LTE.

Therefore, TD-LTE faces the question of internationalization first, "however the quality of the spectrum is one of the important factors affecting the internationalization of TD-LTE," said He Ting-run, the National Institute of Radio Frequency Spectrum Management. Therefore, if TD-LTE wants to go global and blossom in the world, it must first resolve the contradiction between more and fewer spectral resources.

"Digital Dividend" 700MHz Frequency Band Retired

The 2007 World Radiocommunication Conference decided that the 698 to 806/862 MHz should be referred to as the 700 MHz frequency band. After digitizing analog television, a part of the frequency is released for mobile communications or public safety services (called “digital dividends”).

At present, most developed countries have already completed the analog-to-digital conversion of television broadcasting systems. For example, in March 2012, the European Parliament passed a five-year radio spectrum policy plan, which requires all EU members before January 1, 2013. The country should authorize the use of the 700 MHz band for wireless broadband communications unless individual exemptions have been obtained prior to that date. At the same time, developing countries have also begun analog-digital conversion of television broadcasting systems.

700MHz is the golden band, and the three major domestic operators love it. However, the analog-to-digital conversion process in our country is quite slow, and even the radio and television department stated that it will postpone the completion of the A/D conversion time from 2015 to 2020.

In response, He Ting-run said: "Five years is the time of change in a generation of mobile communications. When China's broadband strategy has clearly received benefits in 2020, our country's frequency has not yet come out. How can it be?"

"nail households" PHS withdrawals

Previously, the 1900 to 1920 MHz total frequency of 20 MHz released by PHS's withdrawal has caused some discussion in the industry, and with the forthcoming issuance of 4G licenses, the three major operators released the PHS after the PHS was released. Competition for precious spectrum resources has also become increasingly fierce.

In fact, as early as January 2009, the Ministry of Industry and Information Technology issued a notice requesting that PHS should complete its clean-frequency network retirement work by the end of 2011, and its frequency should be recovered without conditions. However, as of the end of the first quarter of 2013, the number of PHS users was still about 10 million. It is still unclear when the completion of clearing the frequency of withdrawal, and PHS has become the most stubborn “nail household”.

Back in 2002, the Ministry of Information Industry issued the "Circular on the Third Generation Public Mobile Communication System Frequency Planning Issues." The notification requires that the frequency of 1880 to 1920 MHz be planned to be the main use frequency band of TDD, indicating that it is small from the date of the announcement. Smart Link's 20MHz frequency has been legally used as a 3G TDD standard. According to this rule, PHS's backoff frequency for TD-SCDMA can be used for the development of TD-LTE. However, the spectrum originally supposed to belong to TDD has not been implemented.

"If the national radio regulatory agency does not issue new regulations, all operators holding TD-LTE licenses have the right to apply for the use of PHS's frequency of withdrawal." He Ting-run said, "But it should be planned by the national radio regulatory agencies. And distribution, not negotiation and transfer between related operators."

Spectrum sharing is a must-see

In addition to the three outstanding contradictions mentioned above, there is a huge gap in spectrum resources in the future that cannot be ignored. According to reports from Ericsson and Huawei, the total demand for low user density in the world in 2020 is 1240 MHz, and the total demand for high user density is 1880 MHz. The GSMA predicts the total demand in the world in 2020 from 1600 MHz to 1800 MHz.

In this regard, He Ting-run said: "The physical resources of the spectrum are limited and fixed, and the realization of sharing of spectrum resources is an effective way to increase the efficiency of the utilization of spectrum resources and enhance the ability to ensure the protection of spectrum resources."

The cognition of traditional radios stays at the spectrum sensing level, that is, the use of idle frequencies for business transmission. “But the dynamic sharing of spectrum is the best choice. From the perspective of spectrum management and control architecture, the optimal allocation of spectrum resources requires real-time knowledge of the electromagnetic environment, users, services, channels, and networks, and they are aggregated into the spectrum access system ( SAS) processing nodes for overall optimization." He Ting-run said.

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