HSUPA

Technology

HSUPA adds a new transport channel to WCDMA, called the Enhanced Dedicated Channel (E-DCH). It also features several improvements similar to those of HSDPA, including multi-code transmission, shorter transmission time interval enabling faster link adaptation, fast scheduling, and fast hybrid automatic repeat request (HARQ) with incremental redundancy, making retransmissions more effective. Similar to HSDPA, HSUPA uses a "packet scheduler", but it operates on a "request-grant" principle where the user equipment (UE) requests permission to send data and the scheduler decides when and how many UEs will be allowed to do so. A request for transmission contains data about the state of the transmission buffer and the queue at the UE and its available power margin. However, unlike HSDPA, uplink transmissions are not orthogonal to each other.