The HS-PDSCH is utilized to convey the High Speed – Downlink Shared Channel transport channel. The HS-PDSCH might utilize QPSK or 16QAM modulation. High-Speed Physical Downlink Shared Channel is a channel added to UMTS to increment downlink information rates. This is characterized in Release 5 of the UMTS specifications. It conveys client information and layer 2 overhead bits mapped from the transport channel: HS-DSCH.