The Wall Street Journal is reporting that Sprint will officially announce Friday that it's terminating its planned 15-year agreement with LightSquared for LTE service, leaving the wireless wholesaler without a major partner for its 4G network — a network rendered all but dead by the FCC's ruling that it couldn't be built over GPS interference concerns. Needless to say, the official termination comes as no surprise, and it's something that Sprint has hinted it would do in recent weeks.

LightSquared's 1600MHz network had originally factored prominently into Sprint's LTE deployment strategy over the next couple years, but it's not like the carrier is without a backup plan: it's already in the process of refarming its CDMA and iDEN spectrum to make room for LTE service, and it'll be working with longtime partner Clearwire to deploy TD-LTE in the same 2500MHz band where its WiMAX network currently operates.

The collapse of the deal means that Sprint will owe $65 million in prepayments to LightSquared, money that the beleaguered company will likely desperately need as it fights for its life over the coming months. It just retained some legal big guns to help it through the process, but it won't be easy: earning the right to build out a nationwide network in its spectrum will require convincing a skeptical establishment that it can deploy without affecting something as mission-critical as GPS.