A.A. Malyutin1, M.D. Portnichenko2, A.N. Zyuzin3

1-3 JSC RIE “PROTEK” (Voronezh, Russia)

1-3 protek@protek-vrn.ru

Problem statement. In communication systems with intersymbol interference, improving reception noise immunity is traditionally achieved either by linear equalization, which is inferior in quality to optimal methods, or by lattice equalizers, which provide significantly better performance at the cost of significantly greater computational complexity. This contradiction is particularly acute in multipath decameter channels, where the length of the impulse response can make the use of lattice algorithms practically impossible with available digital signal processing tools.

Purpose. The aim of this work is to develop a hybrid equalizer for multipath communication channels with intersymbol interference, providing the necessary compromise between noise immunity and computational complexity. To achieve this goal, the problem of optimally separating the channel impulse response into two components, processed by a linear and lattice equalizer, respectively, is solved.

Results. A hybrid equalizer is proposed that represents a channel as a series connection of two equivalent subchannels, one of which is equalized by a linear equalizer and the other by a lattice equalizer. A method for factorizing the polynomial representation of the channel impulse response is developed, selecting factors based on the criterion of maximizing the resulting noise immunity or using a simplified heuristic rule related to the location of the polynomial roots in the complex plane. It is shown that this approach allows for focusing computationally complex optimal processing on the most distorting channel components.

Practical significance. The results of this work can be used in the design of receive paths for digital communication systems operating in multipath channels with limited computing resources, primarily in HF and other high-speed data transmission systems. Simulations on standard Prokis channels and on a fading HF channel showed that the proposed hybrid equalizer provides a significant gain over linear equalization, with a moderate performance penalty compared to fully latticed algorithms, which are difficult to implement in practice. The proposed approach also holds promise for use in decision-feedback systems, turbo equalizers, and spatial-temporal equalization of SIMO/MIMO channels.

Malyutin A.A., Portnichenko M.D., Zyuzin A.N. Hybrid equalizer combining trellis-based and filter-based algorithms // Radiotekhnika. 2026. V. 90. № 7. P. 159−167. DOI: https://doi.org/10.18127/j00338486-202607-23

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