FBMC QAM Signal Filtering for Intrinsic Interference Reduction
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Solution Overview
Problem
Conventional Filter Bank-based Multicarrier (FBMC) communication systems face complexity increases due to overlapping filtering of adjacent QAM signals, making it difficult to combine with Multiple-Input Multiple-Output (MIMO) systems and increasing the size of IFFT and FFT sizes K times, leading to intrinsic interference.
Innovation Solution
The method involves sorting QAM signals into groups, filtering them separately using orthogonality of filters, and transmitting the overlapped signals in the time domain to mitigate interference and reduce system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If adjacent QAM signals are spread and overlapped in the spreading process for performing frequency domain filtering, then spectral efficiency is improved, but intrinsic interference occurs and signal recovery becomes impossible
Solution Approach 1:
The patent segments the QAM signals into separate in-phase (real) and quadrature-phase (imaginary) components, arranging them to cross each other in the time-frequency resource. This segmentation allows adjacent signals to be spread and overlapped for frequency domain filtering while the orthogonal arrangement prevents intrinsic interference, enabling both spectral efficiency improvement and signal recovery.
2Ease of manufacture
If the size of IFFT and FFT is increased K times corresponding to the overlapping factor of the prototype filter, then frequency domain filtering is enabled, but system complexity increases
Solution Approach 1:
The patent divides the filtering process into separate operations for in-phase and quadrature-phase components. By segmenting the signal processing into these two orthogonal domains, the system can perform frequency domain filtering with reduced IFFT/FFT sizes compared to conventional approaches, thereby lowering computational complexity while maintaining filtering capability.
Solution Approach 2:
The patent changes the parameter of signal arrangement by using OQAM modulation where in-phase and quadrature-phase components are arranged to cross each other in time-frequency resources. This parameter change enables frequency domain filtering with smaller transform sizes, reducing system complexity while achieving the desired filtering effect.
3Reliability
If OQAM is used to arrange in-phase and quadrature-phase components to cross each other, then signal recovery is enabled, but difficulty in combining with MIMO systems occurs
Solution Approach 1:
The patent segments the modulation process into separate filtering operations for even-indexed and odd-indexed subcarriers, with each group processed independently through orthogonal filters. This segmentation maintains the signal recovery benefits of OQAM while creating a more modular structure that is easier to integrate with MIMO systems, as each spatial stream can be processed independently through the same orthogonal filter bank structure.
Data Source
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AI summary
The present invention relates to a transceiving method and apparatus that enable QAM signal transmission in a filter bank multi-carrier (FMBC) communication system and provides, in particular, a transceiving method and apparatus that enable quadrature amplitude modulation (QAM) signal transmission without intrinsic interference by separating filtering between a sub-carrier having an even index and a sub-carrier having an odd index, and superimposing and transmitting sub-carriers filtered by means of separation. The thus-rendered present invention is a transmission method in the FBMC communication system, the method comprising the steps of: dividing at least two QAM signals into a plurality of groups; performing filtering on each of the plurality of groups; and superimposing and transmitting the QAM signal in the plurality of groups filtered on a time axis. The present invention relates to a transmission method and apparatus, and a corresponding reception method and apparatus.