e., RLC) to recover the data. A general block diagram of the HSDPA
transmission is given in Fig. 7.116.
What this block diagram attempts to show is that the NodeB will use information from the UE,
specifically the CQI and ACK/NACK responses, to determine the code rate and modulation scheme to
be used for the next transmission. The CQI information will inform the NodeB what the best combination
of modulation and code rate the UE can handle for that particular measurement interval is.
3
SF
e aM
l2aK
k0
dk(t tl) # CCH,jk(t tl) # CCH,j(t t1) # Scr(t tl) # S*
cr(t t1) fdt
3
SF
aK
k1
dk(t tl) # CCH,jk(t t1) # CCH,j(t t1) # ZScr(t t1)Z2dt
d0(t) 3
SF
d0(t t1) # ZCCH,j(t t1)Z2 # ZScr(t t1)Z2 dt
434 CHAPTER SEVEN
FIGURE 7.116 HSDPA block diagram.
From
UE
Data
Blocks
CRC
Turbo
Encode
PhyCh
Segment
HARQ
Interleaving
QPSK
QAM
Tx
Chips
Spread
Adaptive Modulation and Coding (AMC)
The ACK/NACK information will inform the NodeB whether the last transmitted HS-DSCH packet
was correctly/incorrectly received, respectively. The integrity of the packet data is determined by the
CRC decoding. The NodeB will use this information to either retransmit the packet, so the UE can correctly
receive it or adjust the HS-DSCH modulation and coding combination to deliver the data.
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