Japan's Softbank Mobile has contracted Ericsson to roll out a HSPA+ network on the 900-MHz band.
Softbank revealed plans to deploy the network in the Tomeihan area, which covers Tokyo, Osaka and Nagoya.
The network will use Ericsson's RBS 6000 base station standard, which is also compatible with W-CDMA and LTE.
Ericsson will provide services including network design, consulting systems integration and network deployment.
Separately, Softbank rival NTT DoCoMo announced it now has over 2 million subscribers to its Xi LTE service.
DoCoMo launched Xi in December 2010, and reached the one million customer milestone almost exactly one year later, meaning subscriptions have doubled in the past three months.
The introduction into the market of the first Xi-compatible tablets in October 2011 and smartphones a month later spurred this adoption boom.
Samsung scored both these firsts, with its Galaxy S II LTE smartphone and Galaxy Tab 10.1 LTE tablet.