LTE-Advanced, standardized in 3GPP Release 10, will enhance LTE into a true 4G mobile communications technology while meeting the IMT-Advanced requirements in terms of peak data rate and spectral efficiency. Carrier aggregation is the most demanded feature of the LTE-Advanced feature set because it will allow network operators worldwide to aggregate their different spectrum holdings.
https://www.youtube.com/watch?v=SrBKna0w2WM