Sales of fixed wireless broadband, where users can't roam as they do on cellphones, will peak and level off in 2007, according to a report published by ABI Research today.

The report said it will taper off in favor of mobile WiMax, which will allow users to handoff from one tower to the next. The prediction that mobile WiMax will overtake fixed WiMax is not surprising given that Sprint Nextel announced last week it plans to begin rolling out a nationwide mobile WiMax network in 2007 and 2008. Also, Kirkland-based Clearwire is installing a proprietary version of fixed WiMax across the country and plans to upgrade to mobile WiMax soon.

"Mobile WiMAX will start to see deployments in 2007, and the crossover point between the two will be late in 2008," said ABI Analyst Alan Varghese.

ABI Research said that in the mobile version there will be three challenges: performance, power consumption and cost.