.., N}
j ???{1, ..., NMP}
candidate list (tj) is compared to the active list (tk), so actively tracked multipaths are not swapped
with the same multipath. Once the active list is removed from the candidate list, the smallest energy
multipath on the active list (Fmin) is compared to the candidate list to determine if a new assignment
into the RAKE is necessary. We have included a small margin, labeled K, so as to prevent adding multipaths
with essentially the same average power as what is being actively combined.
Frequency Lock Loop (FLL). Let us consider the downlink in this AFC example. The NodeB and
UE will use oscillators to assist in the frequency up-conversions and down-conversions of the
WCDMA signal. These oscillators will have some uncertainty of frequency error associated with it.
As shown earlier, frequency offsets rotate the constellation with an angular frequency proportional to
the residual frequency offset present on the signal. We will present a technique called Frequency Lock
Loop (FLL), which is used to estimate the frequency offset present in the received signal ( f) and
then apply a correction signal in an effort to reduce the frequency offset.
The FLL block diagram emphasizes a single RAKE finger.
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