It is said that DoCoMo will chip in half the $309 million capital cost of the project. DoCoMo is said to be investing $4 billion over three years in its LTE plans.
Discussions about the joint venture are still ongoing, says Japan's Nikkei newspaper, but the target date for forming the joint venture is early next year.
The speculation is that the companies are concerned about the growing influence of Qualcomm over the supply of wireless ICs, and the increasing influence of the US.
Qualcomm has an 80% share of the smartphone baseband IC market. Last year, Intel bought another baseband supplier, Infineon.
A potential rival to Qualcomm, ST-Ericsson, has seen its market share decline, its debts increase and its new product lines delayed since being formed in 2009 from the wireless activities of STMicroelectronics, Ericsson and NXP.