3.2.2. Source parameters

The source generates \(K\) information bits: it is the simulation starting point.

3.2.2.1. --src-type

Type:text Allowed values:AZCW RAND USER Default:RAND Examples:--src-type AZCW

Method used to generate the \(K\) information bits.

Description of the allowed values:

Value	Description
AZCW	Set all the information bits to 0.
RAND	Generate randomly the information bits based on the MT 19937 PRNG [MN98].
USER	Read the information bits from a given file, the path can be set with the --src-path parameter.

Note

For the USER type, when the number of simulated frames exceeds the number of frames contained in the files, the frames are replayed from the beginning of the file and this is repeated until the end of the simulation.

3.2.2.2. --src-implem

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

Select the implementation of the algorithm to generate the information bits.

Description of the allowed values:

Value	Description
STD	Standard implementation working for any source type.
FAST	Fast implementation, only available for the RAND source type.

3.2.2.3. --src-fra, -F

Type:integer Default:1 Examples:--src-fra 8

Set the number of frames to process for each task execution. The default behavior is to generate one frame at a time. This parameter enables to process more than one frame when the generate task (from the source module) is called.

The number of frames consumed and produced when a task is executed is called the inter frame level or IFL. Setting the IFL in the source module will automatically affect the IFL level in all the other simulation modules (c.f. Fig. 3.6).

Fig. 3.6 3-way inter frame level in the communication chain.

The IFL also allows multi-user configurations to be simulated (see Fig. 3.7). This configurations is used when using SCMA modulation (see the --mdm-type SCMA parameter).

Fig. 3.7 3-way inter frame level with multi-user channel in the communication chain.

Note

For short frames, increase the IFL can increase the simulation throughput, it can hide task call overheads.

Note

For large frames, increase the IFL can decrease the simulation throughput due the CPU cache size limitation.

3.2.2.4. --src-path

Type:file Rights:read only Examples:--src-path ../conf/src/GSM-LDPC_2112.src

Set the path to a file containing one or more frames (informations bits), to use with the USER source type.

An ASCII file is expected:

# 'F' has to be replaced by the number of contained frames.
F

# 'K' has to be replaced by the number of information bits.
K

# a sequence of 'F * K' bits (separated by spaces)
B_0 B_1 B_2 B_3 B_4 B_5 [...] B_{(F*K)-1}

3.2.2.5. --src-start-idx

Type:integer Default:0 Examples:--src-start-idx 42

Give the start index to use in the USER source type. It is the index of the first frame to read from the given file.

3.2.2.6. References

[MN98]

M. Matsumoto and T. Nishimura. Mersenne twister: a 623-dimensionally equidistributed uniform pseudo-random number generator. ACM Transactions on Modeling and Computer Simulation (TOMACS), 8(1):3–30, 1998. doi:10.1145/272991.272995.