DS525 Datasheet, PDF (7/13 Pages) –

802.16e CTC Encoder v3.0
Figure 4(c) shows the effect of decreasing the block size. Since it takes longer to read a large block out
of memory than it does to write smaller one in, the memory controller needs to wait for the larger block
to be read out before it can rotate the buffers. To avoid overrun on the input, RFFD is held Low until the
memory read operation has completed.
Figure Top x-ref 4
a) Memory utilization for constant block size (N)
D FD_IN
DATA_IN
WRITE
i_PRECODER
s^READ
ENCODER
READ
c_RDY
N M3
N M2
N M1
N M1
N M3
N M2
N M2
N M1
N M3
N M3
N M2
N M1
N M1
N M3
N M2
o _{b) Memory utilization for increasing block size (n to N, where N > n)}
n _{FD_IN}
t _{DATA_IN}
i ^WRITE
n PRECODER
READ
ENCODER
u READ
RDY
n M3 n M1 n M2
N M3
n M2 n M3 n M1 n M2
n M1 n M2 n M3 n M1 n M2
N M1
N M3
N M2
N M1
N M3
N M3
N M2
N M1
e _{c) Memory utilization for decreasing block size (N to n, where n < N)}
d _{FD_IN}
DATA_IN
N M3
n M1
n M2
n M3 n M1 n M2 n M3 n M1 n M2
IP _WRITE
PRECODER
N M2
N M3
n M1 n M2
n M3 n M1 n M2 n M3 n M1
READ
ENCODER
READ
N M1
N M2
N M3
n M1 n M2 n M3 n M1 n M2 n M3
RDY
Figure 4: Triple-Buffering Memory Utilization
DS525 April 24, 2009
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Product Specification