Carrier aggregation brings higher data rates, higher capacity for bursty applications such as browsing, and an enhanced broadband experience for all users. HSPA+ commercialized the first step, aggregation across two carriers (aka dual-carrier) back in 2010, as part of Rel. 8. Carrier aggregation has been evolving since then, bringing it to the uplink, more carriers in the downlink, more bands, aggregation with unpaired spectrum and more.
April 15, 2014https://www.qualcomm.com/media/documents/files/hspa-carrier-aggregation-evolution.pdfPrakash SangamTechnical Marketingnonenone
April 15, 2014