I've heard that 5G was to use both the 2.4 GHz and 5GHz unlicensed bands simultaneously, to the detriment of home routers. source
Extending LTE to unlicensed spectrum at 5GHz is an enticing prospect
Extending LTE-Advanced to unlicensed spectrum is a major feature of 3GPP Release 13, due to be frozen in March 2016. Previously this was referred to as LTE-Unlicensed (LTE-U), but 3GPP uses the name LAA to reflect the role of licensed spectrum in its operation.
Yep - I think the phrase 'sub-6Ghz' was to avoid the conflict around the attack on our 5Ghz wifi