The UE then has approximately 7.5 time slots to
process the data and determine if an ACK or NACK should
be transmitted on the uplink HS-DPCCH.
If the HS-DSCH demodulation was successful, then an
ACK will be sent by the UE and the NodeB will send a new
data indicator bit enabled along with new packet data in the
next subframe. However, if a NACK was transmitted, then
the new data bit indicator would be disabled and possibly a
new redundancy version (HARQ) be applied.
Next we decreased the inter-TTI distance to 2, in order to
observe the retransmission behavior. We have shown three
time-interleaved processes in the figure in Fig. 7.124. An
inter-TTI distance of 1 means that data is transmitted every
subframe. This is used to generate more data throughput to
the UE and is called H-Set 3 in the 3GPP standard.
7.7.4 NodeB HSDPA Architecture Enhancements
The HARQ and scheduling of HS-DSCH is included in the MAC layer. The transport channel HS-DSCH
is controlled by the MAC-hs. A simplified radio interface protocol architecture is given in Fig. 7.125.
Let us discuss the deployment of the HS-DSCH and HS-SCCH channels in a cell. The HS-SCCH
is a shared control channel that could be configured to have a constant transmit power.
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