China Unicom (Hong Kong) Ltd, the nation's second-largest telecom carrier by subscribers, announced on Thursday that all of its future 3G smartphones would support the high-speed mobile network with a download speed of up to 21Mbps.

The company expects to fulfill the target starting from the second half of this year, said Zhou Youmeng, general manger of China Unicom's marketing department.

Currently, almost all the high-end WCDMA 3G flagship smartphones promoted by China Unicom already support the 21Mbps network, she said.

China Unicom adopted WCDMA technology to deploy its 3G network in 2009. The company is now upgrading the WCDMA network into a faster HSPA plus network, which may reach a download speed of up to 21 Mbps.

"The next step for China Unicom is to include affordable smartphones costing 1,000 yuan in this class," Zhou said.

On Thursday, Nokia launched the Lumia 520, the first entry-level Windows Phone 8 device supporting China Unicom's high-speed HSPA plus network, indicating that Windows Phone devices had started to enter the 21Mbps network era.

Before that, ZTE and CoolPad, two Chinese mobile phone vendors, released two affordable Android handsets, which were compatible with China Unicom's high-speed network.

As of February, China Unicom had 83.5 million 3G subscribers, an increase of 82 percent year-on-year. The company sold more than 21 million WCDMA devices in the first two months of this year, up 87 percent year-on-year.