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Belief-propagation Receivers for Nonlinear OFDM

This is a communication system simulation code for nonlinearly distorted OFDM with receivers based on generalized approximate message passing algorithm. For more details, see Ref [1, 2].

Getting Started

This simulation code relies on Armadillo (C++ library for linear algebra & scientific computing). Other than that there are no external dependencies.

Prerequisites

Firstly, you need to install Armadillo C++ library. You can download a copy of Armadillo C++ library from the official web-site (http://arma.sourceforge.net/), or you can use pre-built Armadillo packages provided by many Linux-based operating systems. Personally, I use Visual Studio 2019 and install Armadillo via vcpkg package manager (https://github.com/Microsoft/vcpkg).

Running the simulation

The principal way to run simulation is via command line interface with simulation parameters specified in cfg.txt file.

Simulation parameters

The parameters that can be specified in cfg.txt file are given in the table below:

Parameter Description
N the number of subcarriers in oversampled signal
Nu the number of nonzero subcarriers (i.e., oversampling factor M=N/Nu)
I_max the maximum number of iterations
G0 the input signal scaling factor
s_scale the noise variance scaling factor
B the damping factor
rand_seed the random seed
EbNo the signal-to-noise ratio per bit (array, e.g. 7.75 8.0 8.25)
L_SNR the number of OFDM symbols to simulate per EbNo (array)
qam_order the QAM modulation order (supported: 4, 16, 64)
enable_multipath_channel set this value to 1 to simulate Rayleigh block-fading channel
Channel taps the number of channel taps
Channel delay spread the channel RMS delay-spread (normalized)
enable_oob_filtering_tx set this value to 1 to enable out-of-band filtering in the transmitter
enable_oob_filtering_rx set this value to 1 to enable out-of-band filtering in the receiver
post_correction set this value to 1 to enable 1-bit correction post-processing

Example configuration file:

N = 16384
Nu = 4096
I_max = 75
G0 = 0.0
s_scale = 0.71
B = 0.875
rand_seed = 12345
EbNo =  7.75 8.0 8.25 
L_SNR = 1000 1000 1000
qam_order = 16
enable_multipath_channel = 0
enable_oob_filtering_tx = 0
enable_oob_filtering_rx = 0
post_correction = 1

Getting results

The simulation results are stored in:

  • EbNo.txt (all simulated EbNo values)
  • BER.txt (the BER result for each EbNo value)
  • FER.txt (the FER result for each EbNo value)
  • log.txt (all the output you see on the screen during simulation)

References

  1. S. Zhidkov and R.Dinis “Belief Propagation Receivers for Near-Optimal Detection of Nonlinearly Distorted OFDM Signals,” 2019 IEEE 89th Vehicular Technology Conference (VTC2019-Spring), May 2019 Download
  2. S. Zhidkov, "Orthogonal transform multiplexing with memoryless nonlinearity: a possible alternative to traditional coded-modulation schemes,“ in Proc. 9th International Congress on Ultra Modern Telecommunications and Control Systems (ICUMT-2017), Munich, Germany, November, 2017 Download

Authors

License

This project is licensed under the MIT License - see the LICENSE.md file for details

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