On the uplink,
the NodeB receiver performs slightly different processing. In this case, the pilot bits are sent on the
Q-channel while the data bits are sent on the I-channel. In other words, they are quadrature multiplexed.
The block diagram in Fig. 7.65 represented a single finger in the RAKE; these operations will be
repeated for each finger since it is well known that differing multipaths have independent fading.
Let us shift our attention to the uplink for now. The NodeB received signal in a flat fading channel
is given as
(7.72)
After multiplying and despreading by the control channel (CCH) OVSF code, we have
(7.73)
where the DCH has been removed by forcing orthogonality between DCH and CCH. Since the pilot
bits vary with the time slot, we next depilot the despread symbol sequence, which gives
(7.74)
(7.75) r ~
1(k) j # PG # Np # h(k) n^(k)
r ~
1(k) aNp
k1
r1(k) # p*(k)
r1(t) h(t) # j # p(t) # a256
k1
ZCCCH(tk) Z2 # ZScr(tk) Z2 n ~
(t)
r(t) 5d(t) # CDCH(t) j # p(t) # CCCH(t)6# Scr(t) # h(t) n(t)
y(k) PG # h(k) n ~
(k)
Z pCPICH(k) Z2 1
x(k) PG # pCPICH(k) # h(k) n ~
(k)
394 CHAPTER SEVEN
CPICH Despreader
X MA
Scr
X X
CCPICH p*
X
CDPCH
( )*
r
X
hi(t)
h(t)
DPCH Despreader
Channel
Compensation
Depilot & Channel
Estimation
Finger Output
x(t)
y(t)
SF
??
256
??
FIGURE 7.
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