A short informative blog from WirelessMoves provides a comparison of how UMTS and LTE deal with limited uplink power of mobile devices.

When uplink power for a UMTS E-DCH (HSUPA) transmission reaches a maximum, the number of simultaneously used codes can be reduced, a more conservative coding can be employed for additional redundancy and the modulation order can also be changed.

In LTE, modulation and coding can also changed as needed. And in addition, there's a third parameter: LTE uses an OFDM air interface, or to be more precise, SC-FDMA in the uplink direction.

See original blog for more details.