Note the
HSDPA evolution discussions added higher-order modulation schemes, say 64-QAM, to the available
set.
As discussed above, the HS-DSCH works in conjunction with the HS-SCCH. There is a time slot
overlap between these two physical channels. The HS-SCCH is split up into two parts: The first part
describes the number of multicodes and modulation schemes used, while the second part describes
the redundancy version, HARQ process, transport channel block size, new data indicator, constellation
order, UE identity, and channelization code set. The HS-SCCH encoding procedure is given in
Fig. 7.119.
The HS-SCCH decoding performance is critical since this will affect the decoding of the HSDSCH
and possibly lower the downlink throughput. The 3GPP standard proposes various Fixed
Reference Channels (FRCs) to evaluate the downlink receiver performance. The UE capability is
currently placed into 16 categories (see Table 7.2).
3G WIDEBAND CDMA 435
FIGURE 7.117 HARQ retransmission possibilities.
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First Transmission Retransmission
Chase Combining
First Transmission Retransmission
IR Combining
Combined Packet Combined Packet
Systematic
Parity 1
Parity 2
In Fig.
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