 Similarly 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.