INVERTIGATION THE SIGNAL MODULATION TYPES IN THE FIFTH GENERATION MOBILE TELECOMMUNICATION SYSTEMS

Abstract

Some issues on the creation of the fifth-generation mobile communication systems are considered. The basic requirements set to the fifth generation mobile communication systems are introduced. The most important issues are: the frequency range selection, the signal modulation type selection, the error-correcting coding of the data, the methods to increase the data rate and the improvement of the signal noise immunity. The choice of OFDM (Orthogonal Frequency Division Multiplexing) as the most proper signal modulation is substantiated. The experimental results of the OFDM modulation for a different number of subcarriers and different values ​​of modulation index of subcarriers are presented. The maximum data transfer rate optimization in terms of a fixed frequency band is considered. In order to ensure the requirements of high-speed data transmission of several Gb/s, according to the law of Shannon, the bandwidth of channels of the fifth-generation mobile communication systems is justified. With the software-defined radio system SDR (Software Defined Radio) NI USRP-2952R in the mode of reception-transmission, dependences of the data rate from the type of modulation of subcarriers and the type of coding, in the frequency band of 20 MHz,  and the dependence of EVM (Error Vector Magnitude) from signal / noise ratio for the OFDM signal are obtained. The dependencies are obtained for a different number of subcarriers and different types of modulation of subcarriers (from QPSK to QAM-64).