T-Mobile said it will add multicarrier HSPA+ next year, doubling its peak download rates to 42 Mbps. By stacking carriers, HSPA+ can see a data speed increase without increasing total capacity. T-Mobile USA's senior director of engineering and operations, Mark McDiarmid, told Connected Planet at the 4G World show this week that the operator was still in the process of completing its nationwide upgrade to 21Mbps HSPA+, but would "go really big on multicarrier in 2011. The upgrades in many places are well in hand." Article