FBMC Equalization Using Parallel Filterbanks and Derivatives
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Solution Overview
Problem
Filterbank multicarrier (FBMC) modulations face challenges in robustness against channel frequency selectivity, leading to inter-symbol and inter-carrier interference, which existing equalization techniques fail to adequately address due to high computational complexity and suboptimal performance.
Innovation Solution
A method involving serial-to-parallel conversion of received signals, processing through multiple parallel filterbanks using time-domain derivatives of the original filter, and weighting the outputs to achieve effective equalization, reducing computational complexity and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional equalization schemes are applied to FBMC signals in full time-frequency generality, then equalization performance is improved, but computational complexity increases significantly
Solution Approach 1:
The patent divides the FBMC signal into multiple parallel subcarrier streams through serial-to-parallel conversion. Each subcarrier is then processed independently by dedicated equalizers, transforming a complex full time-frequency equalization problem into multiple simpler parallel processing tasks, thereby reducing overall computational complexity while maintaining equalization performance.
Solution Approach 2:
The patent transforms the equalization approach from full time-frequency domain processing to a structure that processes each frequency subcarrier independently with parallel filters. This dimensional decomposition allows the system to achieve effective equalization without the computational burden of complete time-frequency joint processing.
2Device complexity
If single tap per-subcarrier equalizers are used, then computational complexity is reduced, but inter-symbol and inter-carrier interference cannot be compensated
Solution Approach 1:
The patent combines multiple parallel filterbanks processing different time-domain derivatives of the original prototype filter. By merging the outputs of these K parallel filterbanks with appropriate weights, the system achieves effective compensation of inter-symbol and inter-carrier interference while maintaining lower computational complexity than traditional full equalization schemes.
Solution Approach 2:
The patent changes the filter parameters by using successive time-domain derivatives of the original prototype filter in each parallel filterbank. This parameter variation allows the system to capture different aspects of channel distortion, enabling effective interference compensation without requiring complex full-matrix equalization.
3Device complexity
If current FBMC transceivers obviate distortion by assuming perfect reconstruction conditions, then device complexity is reduced, but performance degrades in frequency selective channels
Solution Approach 1:
The patent applies preliminary equalization processing through multiple parallel filterbanks before final signal reconstruction. By preprocessing the received signal through K parallel filterbanks with different prototype filter derivatives and applying appropriate weighting, the system compensates for channel distortion in advance, achieving robust performance in frequency selective channels without requiring complex post-processing.
Data Source
AI summary
A method for equalizing the received signal in communications based on filterbank multicarrier modulations and, more particularly, to such a method and system especially advantageous in situations where the channel frequency selectivity is exceptionally high. The method significantly improves the performance of traditional filterbank equalization algorithms based on finite impulse response filters at the output of the receive filterbank. Furthermore, the system consists of multiple parallel stages, the number of which can be tuned to achieve a good compromise between performance and computational complexity. Thanks to this modular structure, and to the fact that most of the architecture can be efficiently implemented using fast Fourier transforms, the system presents a very low computational complexity compared to more traditional equalizers for filterbank multicarrier modulations.