The HS-DSCH is evolved from the DSCH introduced in W-CDMA Release 99 to enable time-multiplexing different user transmissions.
During this process, the number of bits at the output of the channel coder is matched to the total number of bits of the HS-PDSCH set to which the HS-DSCH is mapped.
An example HS-DSCH channel coding is shown in Figure 1.
The effective code rate for any HS-DSCH configuration can be calculated if the transport block size, the number of HS-PDSCHs, and the modulation format are known.
The number of HS-PDSCHs or code channels that map onto a single HS-DSCH can vary dynamically between 1 and 15.
The second and third slots carry the HS-DSCH channel coding information, such as the transport block size, HARQ information, the RV and constellation versions, and the new data indicator.
The HS-DPCCH carries uplink feedback signalling related to the downlink HS-DSCH transmission.