Simulation of CDMA communication system

This program simulates a basic CDMA communication system using Matlab. It includes the following components:

cdma.m is the main file.

Components and options

Input voices

Four .wav files to simulate four users (variables x1, x2, x3 and x4). The program plots these input signals.

Quantization

This program plots the first input signal with the levels of quantization and the quantized signal.

nivel: the number of levels for quantization.

opcion: quantization processes. Available options:

• 1 - Uniform
• 2 - Mu-Law
• 4 - A-Law

errorcuantizacion: quantization error.

Multiple Access

opt: type of code for CDMA access. Available options:

• 1 = Orthogonal (Synchronous)
• 2 = Random (Asynchronous)

gp: GP value for correlation matrix.

Modulation

BPSK modulation is performed.

AWGN Channel

This module simulates a AWGN channel where noise is added to the communication.

ebno: Eb/N0. It is the energy per bit to noise power spectral density ratio. Value between 1 and 10, where 10 is for the least noisy channel.

Output

BER Curves

This module uses a loop in order to simulate an AWGN channel with several Eb/N0 values (between 1 and 10)m and it plots the BER curve for the selected voice.

Demodulation and the division of users are performed in this loop.

errorpe: probability of error. It gives the average rate of occurrence of decoding errors.

Final message

You can either select to play one user voice or all users voices. The program plots the output signal.

Graphs

Acknowledgements

This program was developed during the communication course "Comunicación y codificación digital" at Universidad de las Fuerzas Armadas ESPE.