The diagram in Fig. 7.98 shows a onefinger
RAKE receiver. In practice, the RAKE will have many fingers actively demodulating and combining
multipaths. Hence the FED output z(t) should be summed across the pilot bits of interest,
averaged across all fingers, and averaged across all receive antennas to create a reliable estimate of
the received residual frequency offset.
Large residual frequency offsets are extremely detrimental to the overall system performance, if
left uncompensated. Large frequency offsets prevent extended accumulation lengths, degrade CE,
and can diminish system capacity. The NodeB requirement is 0.05 ppm, and the UE requirement is
0.1 ppm.
TFCI Decoding. In this section, we will briefly review the generation of the TFCI bits. The
transport channel demultiplexor, in the receiver, will use the information to extract parameters to
aid it in decoding the received physical channel. An example of what info is conveyed by these
control bits is the number of transport channels, the size of the transport block, power ratios, and
so forth.
We begin by presenting the generation or encoding procedure of the TFCI bits. We briefly discuss
the mapping of these bits to the physical channel. Next we present the TFCI decoder and discuss its
interaction with the physical channel.
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