Channel Structure with HSDPA and HSUPA

Channel Structure with HSDPA and HSUPA

E-HICH -> HARQ ACK/NAK information is sent on a new downlink dedicated physical channel, the E-DCH Hybrid ARQ Indicator channel.

E-AGCH -> Scheduling grants sent from the scheduler to the UE, using the shared E-DCH Absolute Grant Channel.

The E-AGCH is sent from the serving cell only as this is the cell having main responsibility for the scheduling operation and is received by all UEs with an E-DCH configured. It is typically used for large changes in the data rates

E-RGCH -> Scheduling grant information can also be conveyed to the UE through and E-DCH Relative Grant Channel. It is typically used for small adjustment during on going data transmission.

E-DPCCH -> In the uplink, control signaling is required to provide the NodeB with the necessary information to be able to demodulate and decode the data transmission.

Even though serving cell has this information but non serving cells in soft handover clearly don't have this information. Also E-DCH also supports non-scheduled transmission. Hence there is a need of out-band signaling in UL.

E-RGCH -> Scheduling grant information can also be conveyed to the UE through and E-DCH Relative Grant Channel. It is typically used for small adjustment during on going data transmission.
E-DPCCH -> In the uplink, control signaling is required to provide the NodeB with the necessary information to be able to demodulate and decode the data transmission. Even though serving cell has this information but non serving cells in soft handover clearly don't have this information. Also E-DCH also supports non-scheduled transmission. Hence there is a need of out-band signaling in UL.