Subframe Segmentation (Sp Mode Only); Sliding Windows And Sub-Blocks Segmentation (Example With 5 Sub-Blocks, Frame Length 20730); Examples For Num_Block, Num_Subblock, Num_Sw, And Win_Rel - Texas Instruments TURBO-DECODER COPROCESSOR 2 TMS320C6457 DSP User Manual

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Figure 96. Sliding Windows and Sub-blocks Segmentation (Example with 5 Sub-blocks, frame length
First subblock
Prolog
Only used in SP mode.
in SA mode, start from
known state 0
Sliding Window
Figure 96 show diagrams for the sliding windows for both alpha and beta. Each sliding window consists of
a reliability section and a prolog section. The size of the reliability section can range from 40 to 128 and
the size of the prolog section can range from 4 to 48 in the TCP2. The alpha sliding window starts at the
left and goes right (forward order) and the beta sliding window starts at the right and goes left (reverse
order). See Table 40
Table 40. Examples for NUM_BLOCK, NUM_SUBBLOCK, NUM_SW, and WIN_REL
NUM_BLOCK
40
128
129
256
257
512
3840
16122
20730
8.2

Subframe Segmentation (SP mode only)

A frame needs to be segmented into subframes when working in shared processing (SP) mode; therefore,
the minimum number of subframes is 2. The subframe length should be chosen so that it has a reliable
portion that is both less than 20480 and also a multiple of 256.
Each subframe is then further divided into sub-blocks and sliding windows as described in
subframes except the last one must have the same length and be a multiple of 256.
SPRUGK1 – March 2009
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Frame or subframe (length < 5114)
Middle subblock
Middle subblock
Subblock : 1, 2 or 4 sliding windows
Sliding Window
Sliding Window
for the number of sub-blocks and sliding windows.
NUM_SUBBLOCK
1
1
1
1
2
2
15
63
81
20730)
Middle subblock
Last subblock
Sliding Window
Alpla Reliability Beta
Prolog portion Prolog
portion portion
NUM_SW
0
0
1
1
1
1
1
1
1
Figure 97
TMS320C6457 Turbo-Decoder Coprocessor 2
Architecture
Prolog
Only used in SP mode
subframes (not last).
in SA mode and SP
mode last subframe,
use tail symbols
WIN_REL
40
128
65
128
65
128
128
128
128
shows the segmentation.
Section 8.1. All
61