China Unicom and China Telecom reportedly have applied to the country’s Ministry of Industry and Information Technology (MIIT) for a third batch of hybrid (TDD-FDD LTE) 4G network trials that would extend coverage to a total of 237 cities.

C114.net reported today that the operators are seeking additional trials since the approved 4G coverage in 40 cities doesn’t enable them to meet the needs of their customers. The current trials cover an estimated combined population of 400 million to 500 million, which is less than 40 per cent of China’s population of 1.4 million.

It is not clear how many of the cities will receive approval for TDD-FDD trials, since in the first round not all of the requested cities were approved, the news portal said.

In late August the MIIT approved requests from the two operators to extend their hybrid LTE network trials from 16 to 40 cities, including Beijing and Guangzhou.

Expanding the trials means the number 2 and 3 players can move aggressively to build out their 4G networks and push to gain ground on market leader China Mobile. At the end of September, Unicom had 2.7 million 4G connections and Telecom had 1.3 million, while China Mobile had 41 million, according to GSMA Intelligence.

China Mobile is less interested in an FDD licence since its 3G network is based on TD-SCDMA, which has simplified its migration to TD-LTE.

The first 4G licences officially approved by the government last December were for TD-LTE (using unpaired spectrum). This effectively gave China Mobile an advantage over its rivals, which preferred the more globally popular FDD-LTE (paired spectrum) version of 4G technology.