Nonstationary radio channel

Radio links in mobile communication networks are notable for their considerably nonstationary behavior. Radio channel fading level is considerable. Multipath propagation and significant dispersion of delay are usual phenomena in supported radio channels. In systems of 2G – 3G generation, equalizers were used to alleviate these phenomena but the effect of equalizer implementation remained limited. The use of OFDM signals that assumes the transmission of individual modulation symbols in parallel on multiple subcarriers supporting a quite lengthy clock period and located relatively close to each other in the spectrum.  Exactly this technology was firstly used in Wi-Fi networks and then in all 4G systems. The McWiLL system is no exception from 4G systems and its radio channels transmit OFDM signals. That is why the unwanted effects caused by multipath propagation and fading are significantly suppressed. Frequency-selective distortions are corrected adaptively by means of a corrective tuning to reference signals called “pilot” sequences. Different “pilot” sequences are used for mobile and fixed modes of communication, and this allows for simultaneous corrective tuning of both the spectral characteristics of the radio channels and the antenna pattern that tracks the subscriber. In other known 4G systems the mode of tracking subscribers by the antenna pattern beams is not supported which deteriorates their characteristics noticeably.