CHICAGO, 4G World -- Sprint Corp. (NYSE: S) is working on a new base station platform, codenamed "Project Leapfrog," that would allow it to inexpensively improve coverage across its various networks and reduce the amount of roaming fees it pays to other carriers, LR Mobile has learned.

Several sources here say Sprint wants a base station platform that can support CDMA, 3G EV-DO, WiMax and possibly Long Term Evolution (LTE) in the future so it can cheaply build out multimode coverage across the US.

Our sources say this will have a two-fold benefit for Sprint. The operator can reduce the amount of roaming fees that it is currently paying to carriers such as Verizon Wireless and U.S. Cellular Corp. (NYSE: USM) while getting to switch off more of the legacy Nextel Communications Inc. (Nasdaq: NXTL) towers that it has in its network.

It is not clear what role LTE will play in the project. Sprint is expected to test twin-channel frequency-division duplexing (FDD) LTE in 2011, which would be more akin to the type of technology that Verizon Wireless is using for its deployment. (See Clearwire Plans LTE Tests in the Fall.)

Such a move to LTE could, however, make more sense of the dual-mode LTE and WiMax chipsets that silicon vendors such as Beceem Communications Inc. and Sequans Communications plan to introduce next year. Sequans hasn't officially announced its LTE-WiMax chipset yet but does have one in the works for sometime in 2011; Beceem's silicon should arrive in the first half of the year. LR Mobile asked Sprint's WiMax partner Clearwire LLC (Nasdaq: CLWR) about the project on Wednesday afternoon. CCO Mike Sievert said he had heard of the project and knew it as a "low cost, multimodal" effort but didn't have any further details.

Sprint's Scott Lane, director of 4G product marketing, offered a "no comment" here at the show.

— Dan Jones, Site Editor, Light Reading Mobile