Texas Instruments TURBO-DECODER COPROCESSOR 2 TMS320C6457 DSP Benutzerhandbuch
R
MAX
+
128
while
ǒ
ǒ
N
SB
R
N
SW
*
N
Ǔ w
(R
*
48)
Ǔ
R
+
WIN_SIZE
N
SB
IF
ǒ
R
N
SB
t
WIN_SIZE
Ǔ
R
) )
if(N
v
128)
NSW
+
1, R
+
N
ELSE
NSW
+
2
IF
ǒ
N
SW
+
2
Ǔ
{
{
WIN_SIZE
+
CEIL
ƪ
N
ń
N
SW
ƫ
N
SB
+
CEIL
ƪ
WIN_SIZE
R
MAX
ƫ
R
MAX
+
R
MAX
*
1
}
N
SW
+
N
SW
*
1
8.4
Added Features
8.4.1
Code Rates
www.ti.com
Architecture
Figure 98. Example R Formula
This computation should be done by the DSP CPU. It should be noted that a 1 must be subtracted from
the calculated R value prior to writing to TCPIC1.
the calculated R value prior to writing to TCPIC1.
Note:
The reliability length must fill the above properties to receive a correct decoding. If these
rules are not followed, the MAP will execute, but the BER might not be optimal.
rules are not followed, the MAP will execute, but the BER might not be optimal.
TCP only supports the code rates used in the 3GPP and cdma2000 standards, namely 1/2, 1/3 and 1/4.
TCP2 introduces a more flexible design which always assumes that the code rate is 1/5. Therefore, all
puncturing schemes derived from the rate 1/5 mother code are automatically supported. The received
systematic and parity data is first de-punctured to rate 1/5, then formatted according to the TCP
specifications (see
TCP2 introduces a more flexible design which always assumes that the code rate is 1/5. Therefore, all
puncturing schemes derived from the rate 1/5 mother code are automatically supported. The received
systematic and parity data is first de-punctured to rate 1/5, then formatted according to the TCP
specifications (see
), and finally sent to the TCP.
SPRUGK1 – March 2009
TMS320C6457 Turbo-Decoder Coprocessor 2
63