A.S. Beksaev1, S.V. Zavyalov2, Z.A. Erovenko3
1−3 Peter the Great St. Petersburg Polytechnic University (St. Petersburg, Russia)
1 beksaev_as@spbstu.ru; 2 zavyalov_sv@spbstu.ru; 3 zabalueva_za@spbstu.ru

Formulation of the problem. Filter Bank Multi-Carrier (FBMC) modulation is considered one of the most promising technologies for future-generation communication systems (beyond-5G/6G) due to its high spectral efficiency and low out-of-band emissions. FBMC is also a relevant candidate for implementation in optical systems with Intensity Modulation and Direct Detection (IMDD). The IMDD-FBMC architecture is key for cost-effective segments of optical networks, such as metropolitan and access networks (e.g., PON), where low cost and power consumption are critically important. Such systems are particularly sensitive to chromatic dispersion distortions, leading to pulse broadening and overlap, which causes Inter-Symbol Interference (ISI) and limits the maximum transmission range without the use of complex and expensive compensation systems.

The classic solution in optical IMDD systems has long been Cyclic Prefix Orthogonal Frequency-Division Multiplexing (CP-OFDM), which has disadvantages in the form of reduced spectral efficiency and the need for complex algorithms. The transition from CP-OFDM to FBMC/OQAM allows for an increase in the energy and spectral efficiency of the data transmission system. Unlike CP-OFDM, where a high level of out-of-band emissions creates inter-channel interference in systems with dense wavelength division multiplexing, FBMC applies specific prototype filters (e.g., the PHYDYAS filter) to each subcarrier. The synthesis of a prototype filter can be based on an approach using optimal signals, whose shape is determined as a result of solving corresponding optimization problems, ensuring a minimal level of out-of-band emissions.

Goal. To synthesize an optimal prototype filter for an FBMC/OQAM system that provides maximum out-of-band emission suppression under the constraint of resilience to dispersion-induced distortions in an IMDD channel.

Results. The problem of synthesizing an optimal prototype filter for FBMC/OQAM systems intended for operation in long dispersive optical channels with an IMDD architecture has been solved. Additional constraints in the conditional minimization problem allow for abandoning the use of the universal PHYDYAS filter in favor of a specialized solution synthesized taking into account the specific parameters of the dispersive channel, leading to increased efficiency of optical systems. The synthesized optimal filter demonstrated a significant advantage compared to the reference PHYDYAS filter in the spectral domain (out-of-band emission suppression is 11.8 dB better).

Practical significance. The proposed solution ensures improved spectral efficiency and increased transmission range in cost-effective direct-detection (IMDD) systems, such as access networks (PON) and short-haul lines. Furthermore, this method facilitates denser channel spacing in DWDM systems and enhances reception reliability through stable carrier frequency synchronization. The obtained results will contribute to the formation of adaptive signal algorithms in the concept of Software-Defined Optical Networks (SDON), where filter parameters can be dynamically reconfigured based on measured dispersion or distance, ensuring maximum efficiency and resilience on each network segment. The research results contribute to solving the tasks outlined within the framework of the national project “Data Economy and Digital Transformation of the State”.

Beksaev A.S., Zavjalov S.V., Erovenko Z.A. Evaluation of the efficiency of using the synthesised FBMC form ing filter in optical IMDD systems. Radiotekhnika. 2026. V. 90. № 3. P. 66−75. DOI: https://doi.org/10.18127/j00338486-202603-06 (In Russian)

1. Vaigandla K.K., Benita J. Study and analysis of multi carrier m odulation techniques – FBMC and OFDM. Materials Today: Proceedi ngs. 2022. V. 58. S. 52−56.
2. Chekireva A., Ovsyannikova A., Zavjalov S. BER performance impr ovement in IMDD systems using FBMC signals. 2024 26th International Conference on Digital Signal Processing and its Applications (DSPA). IEEE. 2024. S. 1−5.
3. Chen M., et al. Demonstration of a low-complexity real-time FBM C transmitter for a spectral-efficiency IMDD system. Optics Let ters. 2024.V. 49. № 18. S. 5272−5275.
4. Vardanyan V. A. Imitacionnoe modelirovanie processa peredachi O FDM-signalov po dispersionnomu volokonno-opticheskomu traktu // T-Comm — Telekommunikacii i Transport. 2017. T. 11, № 11. S. 18–24 (in Russian).
5. Biyu You, Liu Yang, Fengguang Lu, et al. FBMC physical layer: a primer. PHYDYAS, January. 2010. V. 25, № 4. P. 7–10.
6. You B., et al. Pilot-based extended Kalman filter for phase noise estimation in CO-FBMC/OQAM systems. Optics Communications. 2019. V. 443. S. 116−122.
7. Nguyen T., Rottenberg F., Gorza S., Louveaux J., Horlin F. Effi cient chromatic dispersion compensation and carrier phase track ing for optical fiber FBMC/OQAM systems. Journal of Lightwave Technology. 2017. V. 35. № 14. S. 2909−2916.
8. Takahashi H., Al Amin A., Jansen S.L., et al. Highly spectrally efficient DWDM transmission at 7.0 b/s/Hz uSING 8 × 65.1-Gb/s coherent PDM-OFDM. Journal of Lightwave Technology. 2010. V. 28. № 4. P. 406–414.
9. Volvenko S. V., Zav'yalov S. V., Makarov S. B. Imitacionnaya mo del' sistemy peredachi spektral'no-effektivnyh signalov s OFDM // Nauchno-tehnicheskie vedomosti Sankt-Peterburgskogo gosudarstve nnogo politehnicheskogo unive rsiteta. 2012. № 4. S. 29–36 (in Russian). 1
10. Shkol'nyj L.A. Optimizaciya formy ogibayushchej radioimpul'sa p o minimumu vnepolosnyh izluchenij. Radiotekhnika. 1975. T. 30. № 6. S. 12−15 (in Russian). 1
11. Makarov S.B., Zav'yalov S.V., Ovsyannikova A.S. Cpektral'naya i energeticheskaya effektivnost' optimal'nyh AFM signalov s uvel ichennymi razmerami signal'nogo sozvezdiya. Voprosy radioelektroniki. Ser. Tekhnika televideniya. 2022. № 2. S. 30−43 (in Russian).