(Reuters) - Sprint Corp , the No. 4 U.S. wireless carrier, is preparing to mortgage a little more than 10 percent of its wireless airwaves to raise cash, the Wall Street Journal reported on Tuesday, citing people familiar with the matter.<div><a href="http://feeds.reuters.com/~ff/reuters/technologyNews?a=c9NpgJ9HWp0:avoFKLAfWHU:yIl2AUoC8zA"><img src="http://feeds.feedburner.com/~ff/reuters/technologyNews?d=yIl2AUoC8zA" border="0" /></a> <a href="http://feeds.reuters.com/~ff/reuters/technologyNews?a=c9NpgJ9HWp0:avoFKLAfWHU:V_sGLiPBpWU"><img src="http://feeds.feedburner.com/~ff/reuters/technologyNews?i=c9NpgJ9HWp0:avoFKLAfWHU:V_sGLiPBpWU" border="0" /></a> <a href="http://feeds.reuters.com/~ff/reuters/technologyNews?a=c9NpgJ9HWp0:avoFKLAfWHU:-BTjWOF_DHI"><img src="http://feeds.feedburner.com/~ff/reuters/technologyNews?i=c9NpgJ9HWp0:avoFKLAfWHU:-BTjWOF_DHI" border="0" /></a></div><img src="http://feeds.feedburner.com/~r/reuters/technologyNews/~4/c9NpgJ9HWp0" height="1" width="1" alt="" />