China’s trunked radios adopt PDT technology


On November 13, 2019, MIIT issued the Notice on Adjusting the Frequency Allocation for Trunked Radio Systems that Operate in the 800MHz Frequency Band. The main points are as follows:


  • China’s trunked radio systems that operate in the 800MHz frequency will adopt TETRA and PDT technology and allocate the bandwidths of 25kHz and 12.5kHz, respectively.


  • The 800MHz trunked radio systems should be used in group call mode and shall not use direct mode operation or normal mode as the daily operational modes.


  • 800MHz trunked radio systems should not occupy less than 70% of the frequency band, users coverage not less than 50%, user capacity not less than 50%, and annual occupancy time not less than 60%.


  • Handheld and vehicle-mounted radios do not need to obtain licenses.


  • National level approval for using the frequencies of 816-821/861-866MHz is no longer necessary.


A trunked radio system is a kind of digital radio system that allows for sharing and allocation of frequencies among users. The system provides users with special services such as group calling, emergency calling, monitoring, priority calling, etc. It is widely used for effective communication in airports, harbours, city railway systems, and city management (public security, firefighting, water supply, air defence, emergency response, or government affairs).


In 2007, MIIT published the Measures for the Administration for Frequencies and Stations of 800MHz Trunking Radio Systems. These measures had four technologies for China’s 800MHz trunked radio systems as a choice for adoption: TETRA (ETSI), iDEN (Motorola), GoTa (ZTE) and GT800 (Huawei). The latter three slowly became obsolete and only TETRA is widely used in China’s government affairs networks, airports, harbours, and rail transit systems.


The PDT technology system was developed by the Ministry of Public Security, along with the participation of many local enterprises. It is based on Europe’s DMR standards but considering the specific demands of Chinese public security clients. Since its development in 2007, the technology has gained great support from the Chinese government. The Ministry of Public Security has specifically invalidated some TETRA-related standards and specifications to pave the way for its development. A complete PDT industry chain was gradually established in the following years.


Compared with TETRA, PDT has a larger scope of coverage but smaller data handling capacity. Additionally, because PDT is still on the preliminary stage of large-scale commercial application, it will confront fierce price competition as well. Despite these challenges, PDT still has a bright prospect. Under the government’s support, PDT technology and standards will continue evolving, and its application will be expanded from its focus on police affairs to wider areas. It seems like China hopes to replicate its previous success in public mobile communications in this professional communication field as well.