In this articles, the technological aspects of the evolution of 5G networks were examined, based on new types of signal-code constructions and allowing to increase the spectral efficiency in comparison with 4G networks. To date, work is underway to establish the future look of mobile 5G networks. The main objectives of 5G networks are: expanding the range offrequencies used, increasing the capacity of networks and improving the efficiency of the network infrastructure based on the use of cloud technologies. One of the main conditions for future generation 5G systems will be an increase in the spectral efficiency (SE) of the transmitted signals through the use of new signal-code constructions (SCC). Analysis of recent studies and publications shows that the reserves for improving the OFDM (Orthogonal Frequency Division Multiplexing) method of modulation with the aim of increasing the SC are almost exhausted. It is necessary to identify replacement approaches that use non-orthogonal in frequency signals, which will increase the spectral efficiency of the 5G network. Today, various methods of multiple access for 5G systems are being investigated, which are not systematized, and in many cases duplicate each other but having different names. Also, not fully revealed the specific features of the new SCC, acceptable for 5G networks. The purpose of this paper is to analyze some of the possibilities for increasing the 5G SE system by using new SCCs.