Estimation of the noise immunity of wireless digital communication systems at influence of noise adjacent receiving channels
Modern digital radio communication systems operate under conditions of severe shortage of the frequency resource, organizing access to the network of subscribers of a multichannel radio communication system requires limiting the signal spectrum to eliminate the mutual influence of the signal on signals of other subscribers of the same network and other communication systems, as well as constantly increasing requirements for digital systems communication data rate, and therefore there is a need to improve spectral efficiency. It should be noted that the use of systems with high spectral efficiency due to the non-linearity of the telecommunication paths, distortions introduced by the signal propagation medium and other effects leads to low energy-efficiency indicators of the radio system. One way to solve these problems is to use signals with a complex time-frequency structure and multi-position modulation. Improving wireless digital communication systems, such as Wi-Max, LTE (Long-Term Evolution) and LTE-Advanced, Wireless Local Area Network (WLAN) standards 802.11n, 802.11ac, 802.11ad, etc., in the direction of increasing bandwidth by The use of signals with multipositional quadrature amplitude manipulation (CAM) with positionality from 512 to 4096 (in perspective) objectively necessitates the need to tighten the requirements for the receiving-transmitting path and, above all, to the parameters of the radio receiver. Thus, the article developed an analytical model and obtained graphical dependences of the probability of an error on a symbol on the average signal-to-noise ratio, which allowed to justify the requirements for selectivity on side channels of receiving radio receivers of digital communication systems when processing signals with quadrature amplitude modulation with different multiplicity.