We should also mention that
support also exists for blind transport format detection.
Two operating scenarios arise when there exists a need for the UE to feedback information to the
NodeB with low latency. These are fast cell selection and closed-loop transmit diversity. Let us discuss
the latter of the two. Here, the NodeB transmits the dedicated waveform via two transmit antennas.
The UE estimates the channel impulse response (CIR) seen by each transmit antenna and then
derives an antenna weight to be fed back to the NodeB, in order to maximize the UE-received power.
This information is conveyed in the feedback indicator (FBI) bit field. In the absence of these cases,
this bit field is not required.
Next we move our discussion to the downlink time-slot structure (see Fig. 1.21). Here, the DPCCH
and DPDCH are time-multiplexed. The same description given earlier about the bit fields applies here
as well.
TABLE 1.7 Uplink DPCCH Fields
Channel Channel
Slot format bit rate symbol Bits/ Bits/
#i (kbps) rate (ksps) SF Frame Slot Npilot NTPC NTFCI NFBI
0 15 15 256 150 10 6 2 2 0
1 15 15 256 150 10 8 2 0 0
2 15 15 256 150 10 5 2 2 1
3 15 15 256 150 10 7 2 0 1
4 15 15 256 150 10 6 2 0 2
5 15 15 256 150 10 5 1 2 2
In Table 1.
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