3.2.8. Quantizer parameters¶
The quantizer is a module that ensures the real numbers transformation from a floating-point representation to a fixed-point representation. This module is enabled only if the receiver part of the communication chain works on a fixed-point representation (cf. the --sim-prec, -p parameter).
Warning
Some decoders are not fixed-point ready, please refer to the decoders documentation for more details.
3.2.8.1. --qnt-type
¶
Type: text Allowed values: CUSTOM
POW2
Default: POW2
Examples: --qnt-type CUSTOM
Select the quantizer type.
Description of the allowed values (\(Y_i\) stands for a floating-point representation and \(Q_i\) for the fixed-point representation of a real number):
Value | Description |
---|---|
CUSTOM |
\(Q_i = \begin{cases} +v_{sat} & \text{when } v_i > +v_{sat} \\ -v_{sat} & \text{when } v_i < -v_{sat} \\ v_i & \text{else} \end{cases}\), with \(v_i = \lfloor \frac{Y_i}{\Delta} \rceil \text{ and } v_{sat} = 2^{p_b - 1} - 1 \text{ and } \Delta = \frac{|p_r|}{v_{sat}}\) |
POW2 |
\(Q_i = \begin{cases} +v_{sat} & \text{when } v_i > +v_{sat} \\ -v_{sat} & \text{when } v_i < -v_{sat} \\ v_i & \text{else} \end{cases}\), with \(v_i = \lfloor Y_i * F \rceil \text{ and } v_{sat} = 2^{p_b - 1} - 1 \text{ and } F = 2^{p_d}\) |
Where \(p_r\), \(p_b\) and \(p_d\) are respectively given through the --qnt-range, --qnt-bits and --qnt-dec parameters.
3.2.8.2. --qnt-implem
¶
Type: text Allowed values: STD
FAST
Default: STD
Examples: --qnt-implem FAST
Select the implementation of the quantizer.
Description of the allowed values:
Value | Description |
---|---|
STD |
Select a standard implementation. |
FAST |
Select a fast implementation, only
available for the POW2 quantizer. |
3.2.8.3. --qnt-range
¶
Type: real number Examples: --qnt-range 1.0
The min/max bounds for the CUSTOM
quantizer.
3.2.8.4. --qnt-bits
¶
Type: integer Default: 8 else see Table 3.8 Examples: --qnt-bits 1
Set the number of bits used in the fixed-point representation.
Note
If the amplitude of the current number exceeds the maximum amplitude that can be represented with the current quantization, then a saturation is applied (c.f. the --qnt-type parameter).
Code | Value |
---|---|
LDPC |
6 |
POLAR |
6 |
REP |
6 |
RSC |
6 |
RSC_DB |
6 |
TURBO |
6 |
TURBO_DB |
6 |
TURBO_PROD |
6 on 8-bit and 8 on 16-bit |
3.2.8.5. --qnt-dec
¶
Type: integer Default: 3 else see Table 3.9 Examples: --qnt-dec 1
Set the position of the decimal point in the quantified representation.
Code | Value |
---|---|
LDPC |
2 |
POLAR |
1 |
REP |
2 |
RSC |
1 on 8-bit and 3 on 16-bit |
RSC_DB |
1 on 8-bit and 3 on 16-bit |
TURBO |
2 on 8-bit and 3 on 16-bit |
TURBO_DB |
2 on 8-bit and 3 on 16-bit |
TURBO_PROD |
2 on 8-bit and 3 on 16-bit |