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 recent years, interest in decameter (HF) range systems has been growing again due to requirements for autonomy, survivability, and expanded coverage areas without using satellite or cellular segments. However, in terms of spectral efficiency in multipath channels, such systems still noticeably lag behind modern communication systems in other frequency ranges. Inaccurate channel parameter estimation due to low signal-to-noise ratio complicates the application of modern detection methods, therefore the development of computationally manageable nonlinear algorithms for the first stage of the turbo equalizer presents both scientific and practical interest.

Purpose. The aim of this work is to develop and substantiate an algorithm for replacing the linear equalizer of the first stage of the turbo equalizer with a computationally manageable lattice detection scheme combining basis reduction using the Lenstra-Lenstra-Lovász method, Schnorr-Euchner search, complexity control using the K-best scheme, and EM-based channel estimation refinement.

Results. A method is proposed that involves applying a combined lattice detection scheme to the first stage turbo equalizer problem, in which basis reduction using the Lenstra-Lenstra-Lovász method is coordinated with Schnorr-Euchner search and complexity management using the K-best scheme. Unlike the classical linear first stage, the proposed approach uses the geometry of the multipath signal in lattice space. Additionally, inclusion of the EM channel estimation algorithm within the inner detection loop is proposed, which allows iterative channel refinement without transitioning to computationally prohibitive strictly optimal lattice algorithms.

Practical significance. The practical significance of the work lies in the possibility of applying the proposed algorithm in modems with turbo equalization designed for robust data transmission under multipath conditions and deep fading. The approach is oriented toward software-hardware implementation in specialized modems, digital signal processors, reconfigurable logic circuits, and software-defined radio systems. The proposed solution can be used to modernize existing communication systems without radically changing the overall receiver architecture.

Malyutin A.A., Portnichenko M.D., Zyuzin A.N. Turbo-equalizer based on lattice search, lattice basis reduction, and EM-based channel estimation // Radiotekhnika. 2026. V. 90. № 7. P. 168−179. DOI: https://doi.org/10.18127/j00338486-202607-24

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