HSUPA (High Speed Uplink Packet Access), or FDD Enhanced Uplink, is designed to improve the performance of uplink dedicated transport channels. Like HSDPA (High Speed Downlink Packet Access), it offers increase data rates, whilst at the same time improving capacity. The FDD Enhanced Uplink upgrade is designed to improve the performance of uplink dedicated transport channels, i.e. to increase capacity and throughput and reduce delay. In order to achieve this three main changes are identified: Node B controlled scheduling – Under the supervision of the RNC, the Node B is able to control the set of TFC (Transport Format Combinations) from which the UE may choose; Hybrid ARQ – this enables the rapid retransmissions of erroneously received data packets between UE and Node B; Shorter TTI (Time Transmission Interval) – the enhanced uplink channel is able to operate with a TTI of 2ms or 10ms.