Study of low power multicarrier modulation for NVIS applications

Abstract

Telecommunications systems have been growing up to such an extent of having almost allthe world connected. In the last years, a lot of articles have been written to create a low-powerand low-cost communication system for places with no telecommunicatons infrastructure.The data collection and data transmission in this kind of area is very challenging due toits hard orography that makes the radio-links have no line of sight propagations. TheGRITS research group of La Salle University has been researching ionospheric radio-links foralmost 20 years. The improvement of the Near Vertical Incidence Skywave (NVIS) channelwhich let signals rebounding in the ionosphere, has allowed the possibility of creating thatmedia with a low cost system benefiting from the ionospheric communication with a 250 Kmdistance link. The aim of this project is the study of the Orthogonal Frequency-DivisionMultiplexing (OFDM) technique and the comparison between narrow-band modulationsstudied in previous studies of HF bands following the STANAG and MIL-STD standards.This type of modulation could be a very important improvement for the NVIS system dueto its robustness. On the other hand, this technique requires much transmission power thanthe other studied modulations, for that reason, the OFDM design needs to be very accurateso that it can be comparable with low-power transmissions.