Ensuring Interference Immunity Under Coherent Signal Reception in an Interactive Multichannel Television System

Systems with high service integration such as MMDS, LMDS, and MVDS have a number of significant advantages. These systems provide various services, including interactive multichannel television broadcasting, and can also be used in terrestrial and cable television distribution networks. In the downlink of the LMDS system, two different modulators are used. Recent studies have proposed adaptive modulation scheme changes. This article defines the signal-to-noise ratio thresholds at which the modulation method changes from one type to another. It is proposed to approximate the influence of impulse and other ultra-wideband interference as the influence of fluctuation noise, and a corresponding formula is derived for calculating the error probability. It is shown that with adaptive modulation changes in an LMDS system, the system becomes more sensitive to measurement errors when the allowable error probability is high.