Sprint made its bet on WiMAX back in 2006 and encountered many problems deploying the network throughout the years. Eventually, Sprint was the first tier-1 operator to offer 4G services in the US back in September 2008, more than two years before its competitors. However, part-owned subsidiary Clearwire, who is in charge of the operation of the network, under delivered in terms of network coverage and subscriber take-up in the two-year period before LTE came to market. Clearwire's WiMAX network only covers 41% of the population whereas Verizon's LTE network which launched in December 2010 currently covers 59%.

WiMAX was primarily designed for fixed wireless broadband access and offered an appealing alternative to 3G for mobile broadband but had little to do with handsets. While mobile broadband remains an important area of interest, smartphones are higher on the operator's agenda and 4G on a smartphone is and will be LTE rather than WiMAX.     

Sprint is keen to not just make up ground on its rivals. It would be one of the first operators in the world to launch LTE-Advanced if it keeps to its timetable. After falling behind its already larger rivals with its LTE rollout, Sprint is eager to avoid a repeat performance with LTE-Advanced. The higher spectral efficiency of LTE-Advanced may also allow Sprint to maintain the unlimited data plans that have been key to its marketing strategy of late.

The announcement made no mention of Clearwire and Sprint's future relationship with its subsidiary is unclear. Clearwire is also looking to transition from WiMAX to LTE-Advanced, but may need to sell some of its spectrum to finance that effort.