Carrier aggregation means more speed and capacity for all users. HSPA+ evolution expands carrier aggregation in many directions. It defines more spectrum band combinations, this allows operators to combine refarmed low-band GSM spectrum (e.g. 900 MHz) with higher bands (e.g. 1900/2100 MHz), and benefit from lower spectrum’s better coverage characteristics. Additionally, there is support for aggregation of up to 8 carriers, and "Supplemental Downlink,” which combines the unpaired spectrum with paired spectrum to increase downlink capacity.