In this case,
users close to the NodeB will have much better performance than those at the cell edge. Since we have
fast link adaptation, it would be prudent to be able to adapt the HS-SCCH transmit power in a similar
fashion. In other words, use TPC on the HS-SCCH and HS-DSCH channels. The feedback information
that can be used is to count the number of times there is no ACK/NACK in the uplink when
the NodeB is expecting one to be present. This implies that the UE did not successfully decode the
HS-SCCH, and hence, its transmit power can be increased the next time the NodeB transmits to that
UE. An ACK/NACK implies, although not strictly limited to, the HS-SCCH was decoded properly
and the HS-DSCH demodulation failed due to poor channel conditions.
436 CHAPTER SEVEN
CRC Attachment (24 Bits)
Bit Scrambling
Code Block Segmentation
Turbo Encoding (R = 1/3)
Physical Layer HARQ
Physical Channel Segmentation
HS-DSCH Interleaving
Physical Channel Mapping
Modulation
Spreading & Sum
FIGURE 7.118 HS-DSCH encoding
overview.
Lastly, the HS-SCCH transmit power can also be adjusted according to the CQI reported by the
UE. When the CQI value is high, the channel conditions are good and the HS-SCCH can be decoded
with reasonable rates.
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