3.2.4.10.2. Turbo Decoder parameters

3.2.4.10.2.1. --dec-type, -D

Type:text
Allowed values:TURBO CHASE ML
Default:TURBO
Examples:--dec-type CHASE

Select the decoder algorithm.

Description of the allowed values:

Value Description
TURBO Select the Turbo decoder, the two sub-decoders are from the RSC code family.
CHASE See the common --dec-type, -D parameter.
ML See the common --dec-type, -D parameter.

3.2.4.10.2.2. --dec-implem

Type:text
Allowed values:STD FAST
Default:FAST
Examples:--dec-implem FAST

Select the implementation of the decoder algorithm.

Description of the allowed values:

Value Description
STD Select the STD implemenation.
FAST Select the fast implemenation from [CTL+16].

3.2.4.10.2.3. --dec-sub-type, -D

Please refer to the RSC --dec-type, -D parameter.

3.2.4.10.2.4. --dec-sub-implem

Please refer to the RSC --dec-implem parameter.

3.2.4.10.2.5. --dec-sub-simd

Please refer to the RSC --dec-simd parameter.

3.2.4.10.2.6. --dec-crc-start

Type:integer
Default:2
Examples:--dec-fnc-crc-ite 1

Set the first iteration to start the CRC checking.

Note

This parameter requires the Turbo code to be concatenated with a CRC to work, see the CRC parameters.

3.2.4.10.2.7. --dec-fnc

Enable the FNC post processing technique.

Note

The FNC post processing technique is detailed in [TLLeGal+16].

Note

This parameter requires the Turbo code to be concatenated with a CRC to work, see the CRC parameters.

3.2.4.10.2.8. --dec-fnc-ite-m

Type:integer
Default:3
Examples:--dec-fnc-ite-m 2

Set the first iteration at which the FNC is used.

See the --dec-fnc parameter.

3.2.4.10.2.9. --dec-fnc-ite-M

Type:integer
Default:10
Examples:--dec-fnc-ite-M 6

Set the last iteration at which the FNC is used.

See the --dec-fnc parameter.

3.2.4.10.2.10. --dec-fnc-ite-s

Type:integer
Default:1
Examples:--dec-fnc-ite-s 2

Set the iteration step for the FNC technique.

See the --dec-fnc parameter.

3.2.4.10.2.11. --dec-fnc-q

Type:integer
Default:10
Examples:--dec-fnc-q 6

Set the search space for the FNC technique.

See the --dec-fnc parameter.

3.2.4.10.2.12. --dec-ite, -i

Type:integer
Default:6
Examples:--dec-ite 8

Set the maximal number of iterations in the Turbo decoder.

If the Turbo code is concatenated with a CRC and if the CRC is checked, the decoder can stop before making all the iterations.

3.2.4.10.2.13. --dec-sc

Enable the Self-Corrected (SC) decoder.

Note

The SC decoder is detailed in [Ton17] (in French).

Note

This parameter requires the Turbo code to be concatenated with a CRC to work, see the CRC parameters.

3.2.4.10.2.14. --dec-sf-type

Type:text
Allowed values:ADAPTIVE ARRAY CST LTE LTE_VEC
Examples:
--dec-sf-type ADAPTIVE
--dec-sf-type CST 0.5

Select a scaling factor (SF) to be applied to the extrinsic values after each half iteration.

This is especially useful with the max-log-MAP sub-decoders (BCJR with the \(\max\) approximation): the SF helps to recover a part of the decoding performance loss compare to the MAP algorithm (BCJR with the \(\max^*\) operator).

Note

The SF technique is detailed in [VF00].

Description of the allowed values:

Value Description
ADAPTIVE Select the adaptive SF, for the first and second iterations a SF of 0.5 is applied, for the other iterations the SF is 0.85.
ARRAY Select an hard-coded array of SFs (c.f. Table 3.3).
CST Set the same SF to be applied for each iterations.
LTE Select a 0.75 SF.
LTE_VEC Select a 0.75 vectorized SF (faster than LTE), used in [CTL+16].
Table 3.3 Hard-coded array of SFs.
Iteration Value
1 0.15
2 0.25
3 0.30
4 0.40
5 0.70
6 0.80
7 0.90
8 0.95

3.2.4.10.2.15. --dec-sub-max

Please refer to the RSC --dec-max parameter.

3.2.4.10.2.16. References

[CTL+16](1, 2) A. Cassagne, T. Tonnellier, C. Leroux, B. Le Gal, O. Aumage, and D. Barthou. Beyond Gbps turbo decoder on multi-core CPUs. In International Symposium on Turbo Codes and Iterative Information Processing (ISTC), 136–140. IEEE, September 2016. doi:10.1109/ISTC.2016.7593092.
[Ton17]T. Tonnellier. Contribution to the Improvement of the Decoding Performance of Turbo Codes : Algorithms and Architecture. PhD thesis, Université de Bordeaux, 2017. URL: https://tel.archives-ouvertes.fr/tel-01580476.
[TLLeGal+16]T. Tonnellier, C. Leroux, B. Le Gal, B. Gadat, C. Jégo, and N. Van Wambeke. Lowering the error floor of turbo codes with CRC verification. IEEE Wireless Communications Letters (WCL), 5(4):404–407, August 2016. doi:10.1109/LWC.2016.2571283.
[VF00]J. Vogt and A. Finger. Improving the max-log-MAP turbo decoder. IET Electronics Letters, 36(23):1937–1939, November 2000. doi:10.1049/el:20001357.