Sprint Nextel may be exploring new funding options for its multibillion WiMAX network and service buildout, according to an article in The Wall Street Journal Thursday.

One option explored in the article includes spinning Sprint’s WiMAX business off and a possible partnership with Clearwire. Headed up by wireless pioneer Craig McCaw, Clearwire is the only other service provider in the United States deploying WiMAX commercially. A handful of service providers have tested the WiMAX technology.

Nearly a year ago Sprint Nextel put a stake in the ground and declared that WiMAX was its next-generation wireless technology of choice. Since then no other wireless carriers have been so bold. With several, such as T-Mobile, still getting their 3G wireless deployed, 4G announcements from Sprint’s rivals might still be a year or more off.

Last August Sprint said it would spend $3 billion to deploy its mobile WiMAX network. That capital investment now may be more problematic for Sprint, however.

The carrier still is trying to work through challenges, such as high wireless-customer churn rates and a falling stock price. The WSJ article speculates that Sprint may be looking for other options that will allow it to fund the building of its next-gen wireless network while keeping investors happy.

The article goes on to say that Sprint also may be in talks with Clearwire to strike a roaming deal. In addition, Sprint may be looking to forge an arrangement with its cable service provider partners.

The WSJ piece describes how the cable companies might pay Sprint a fee to use its WiMAX network.