1. Introduction

Software Defined Radios (SDR) have revolutionized the field of signal processing. Thanks to high computational power of modern processors, typical components of a communication chain, which were used to be implemented in hardware, are now implemented in software. Therefore, multiplexers/demultiplexers, filters, amplifiers, modulation/demodulation are all computer managed rather than independent application-specific integrated circuits (ASICs). The evolution of processing capabilities allowed rapid prototyping in radio frequency (RF) communications. With the aid of developing environments, such as LabVIEW, satellite communication link models can be simulated and valuable information, that once was only possible in theory can now be extracted.

The Project was implemented in the Telecom Lab of Telecom Bretagne at ISAE-SUPAERO, in the context of the Advanced Master in Space Communication Systems.

1.1 Objectives

This project focuses in the implementation of a satellite communication chain. This assignment is to be completed in NI LabVIEW Communications System Design Suite between two USRPs, using QPSK modulation where performance is to be measured in terms of BER. There are things to consider when simulating a communication chain as the one mentioned above.
  • The simulation software, getting acquainted with its functions and features available for modulating, encoding, filtering and demodulating the signal and applying it with USRP.
  • Correct input of parameters such as number of samples per symbol, symbol rate, IQ sampling rate and properly mapping the signal (depending on the modulation chosen) to obtain a good constellation.
  • Filtering is very important, it is necessary to accurately setting the coefficients and bear in mind that filtering will affect the amount of bits transmitted, synchronization parameters might be needed in order to compensate for this effect.
  • The type of coding that is better suited for the simulated chain, setting the right parameters to best improve the performance.

1.2 Authors

Gimenez Silva, Adriana
Paschos, Alexandros

1.3 Supervisor

Franck, Laurent